Dr Mark Welch

Dr Mark Welch

Researcher Mineral Sciences and Systematics

Department: Earth Sciences
Division: ES Mineral and Planetary Sciences Division
Contact: email
Phone: 02079425111 5111

Summary

I am a mineralogical crystallographer researching atomic-scale interactions that control the properties and transformational behaviour of minerals, with the aim of identifying and quantifying correlations between crystal structure, composition and mineral stability. Most of the materials that I research are structurally and chemically challenging and require use of a wide range of advanced diffraction and spectroscopic techniques including X-ray diffraction (XRD), neutron diffraction, MAS NMR, Raman and IR spectroscopies. Although I have used all of these methods extensively, my main technique is single-crystal XRD, using the NHM’s Xcalibur diffractometer housed in the Earth Sciences department. These studies include in situ experiments at variable temperature (to 1400 K) and pressure (to 20 GPa), aimed at understanding the behaviour of minerals at conditions of the Earth’s crust and mantle, particularly in subduction zones, and the implications this behaviour has for mantle processes. I have two main research fields: (i) Hydrous minerals in the Earth’s crust and mantle, and (ii) new-to-science and associated novel technology-related minerals. _________________________________________________________________________________ HYDROUS MINERALS AND THE DEEP MANTLE. A major component of my research relates to quantifying and rationalising the crystal chemistry of geologically important hydrous phases, their protonation phenomena and physical properties relevant to understanding their roles as agents of water transfer into the deep mantle (>200 km) at subduction zones. These hydrous phases include amphibole, chlorite, talc, 10Å -phase, MgSi(OH)6 perovskite and hydrous phase-X K1.5Mg2Si2O7H0.5. Recent advances relate to identifying protonation mechanisms in 10A-phase and the origin of large superstructures coupled to H and K ordering in Phase-X. My work on talc and 10Å-phase demonstrated how the hydrophobic sheet of talc becomes highly hydrophilic by the creation of Si vacancies via SiO4 = (OH)4 and how this modification is central to understanding the stability of 10Å-phase at high pressure and how significantly more water can be taken up by sheet silicates with increasing pressure. In 2007 I was elected a Fellow of the Mineralogical Society of America in recognition of my contributions to understanding the crystal chemistry, thermodynamics and physical properties of geologically important hydrous minerals (amphiboles, sheet silicates, hydroxides). __________________________________________________________________________________ MINERALS NEW TO SCIENCE. I have been involved in the structural characterisation of 17 new-to-science minerals. Most of these minerals have completely new structure topologies, no synthetic analogues and several are related to technologically-significant compounds associated with catalysis, optoelectronics, ionic conduction and frustrated antiferromagnets (Kagome phases). I have served twice (2003-2007 and 2010-2015) on the International Mineralogical Association’s Commission on New Minerals, Nomenclature and Classification, which evaluates over 120 new minerals each year. My recent research on new minerals of the atacamite group, closely-related to the classic frustrated antiferromagnets herbertsmithite Cu3Zn(OH)6Cl2 and tondiite Cu3Mg(OH)6Cl2, has identified new transitional behaviour (dynamic Jahn-Teller distortion) and quantified the effects of small degrees of solid solution upon these transitions. Such information bears on understanding how doping of synthetic herbertsmithites can be used to understand the magnetic properties of this technologically-important group of minerals. __________________________________________________________________________________ I have been associate editor and chief editor for long-established international peer-reviewed journals, including American Mineralogist and Mineralogical Magazine (Chief Editor 2006-2011). I have served on numerous international committees, including Mineralogical Society of America (MSA Award, Public Service Award), Mineralogical Society of Great Britain & Ireland (Officer, Council), IMA (Council), IMA (CNMNC), IMA Medal committee and the International Union of Crystallography (Inorganic Crystal Structures Commission).

Qualifications

Degrees

PhD, University of Edinburgh, Edinburgh

Employment history

Academic

Researcher in Mineral Sciences,, Natural History Museum, Earth Sciences, United Kingdom, 1992 - ongoing

Associate Lecturer in Mineral Sciences, University of Cambridge, Earth Sciences, United Kingdom, 1999 - 2008

NERC Special Fellow & University of Cambridge Research Fellow, University of Cambridge, Earth Sciences, United Kingdom, 1989 - 1992

NERC Post-doctoral Research Fellow, University of Edinburgh, Geosciences, United Kingdom, 1987 - 1989

Highlighted publications

Welch MD, Bindi L, Petříček V, Plášil J (2016) Vacancy pairing and superstructure in the high-pressure silicate K 1.5 Mg 2 Si 2 O 7 H 0.5 : a new potential host for potassium in the deep Earth. Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials, 72 (6) : 822 - 827. doi: 10.1107/S2052520616014049

Welch MD, Rumsey MS, Kleppe AK (2016) A naturally-occurring new lead-based halocuprate(I). Journal of Solid State Chemistry, 238 : 9 - 14. doi: 10.1016/j.jssc.2016.03.005

Welch MD, Rumsey MS (2013) A new naturally-occurring nanoporous copper sheet–silicate with 6482 cages related to synthetic “CuSH” phases. Journal of Solid State Chemistry, 203 : 260 - 265. doi: 10.1016/j.jssc.2013.04.019

Hawthorne FC, Oberti R, Harlow GE, Maresch WV, Martin RF, et al. (2012) Nomenclature of the amphibole supergroup. American Mineralogist, 97 (11-12) : 2031 - 2048. doi: 10.2138/am.2012.4276

Welch MD, Camara F, Della VenturaG, Iezzi G (2007) Non-ambient in-situ studies of amphiboles.. MSA Reviews in Mineralogy & Geochemistry, 67 : 223 - 260.

Welch MD, Pawley AR, Ashbrook SE, Mason HE, Phillips BL (2006) Si vacancies in the 10-A phase. American Mineralogist, 91 (10) : 1707 - 1710. doi: 10.2138/am.2006.2319

Fellowships

Fellow of the Mineralogical Society of America, 2007 - on going.

Fellow, Selwyn College, University of Cambridge, 1989 - 1993.

University of Cambridge Research Fellowship, 1989 - 1992.

NERC Special Fellowship, University of Cambridge, University of Cambridge, Cambridge, Cambridge, United Kingdom, 1989 - 1992.

NERC postdoctoral research fellowship, University of Edinburgh, University of Edinburgh, Edinburgh, Edinburgh, United Kingdom, 1987 - 1989.

Committees

Member, Mineralogical Society of America Public Service Award, 2017 - on going.

Member, International Union for Crystallography Commission on Inorganic Structures, 2016 - on going.

Member, Mineralogical Society of America Award, Mineralogical Society of America, Chantilly, United States, 2014 - 2016.

Member, IMA Commission on New Minerals, Nomenclature & Classification, 2013 - on going.

Member, IMA Commission on New Minerals, Nomenclature & Classification, 2003 - 2007.

Editorships

Editor in chief, Mineralogical Magazine, Mineralogical Society of Great Britain & Ireland, 2006 - 2011.

Guest Editor, American Mineralogist, Mineralogical Society of America, 2004 - 2004.

Associate editor, Mineralogical Magazine, Mineralogical Society of Great Britain and Ireland, 2001 - 2004.

Associate editor, American Mineralogist, Mineralogical Society of America, 1999 - 2003.

Publications

Welch M, Still JW, Rice CM, Stanley CJ (2017) A new telluride topology: the crystal structure of honeaite Au 3 TlTe 2. Mineralogical Magazine, 81 (3) : 611 - 618. doi: 10.1180/minmag.2016.080.112

Mitchell R, Welch M, Chakhmouradian A (2017) Nomenclature of the perovskite supergroup: A hierarchical system of classification based on crystal structure and composition. Mineralogical Magazine, 81 (3) : 411 - 461. doi: 10.1180/minmag.2016.080.156

Rice C, Welch M, Still J, Criddle A, Stanley C (2016) Honeaite, a new gold-thallium-telluride from the Eastern Goldfields, Yilgarn Craton, Western Australia. European Journal of Mineralogy, 28 (5) : 979 - 990. doi: 10.1127/ejm/2016/0028-2559

Welch MD, Bindi L, Petříček V, Plášil J (2016) Vacancy pairing and superstructure in the high-pressure silicate K 1.5 Mg 2 Si 2 O 7 H 0.5 : a new potential host for potassium in the deep Earth. Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials, 72 (6) : 822 - 827. doi: 10.1107/S2052520616014049

Welch MD, Kleppe AK (2016) Polymorphism of the hydroxide perovskite Ga(OH)3 and possible proton-driven transformational behaviour. Physics and Chemistry of Minerals, 43 (7) : 515 - 526. doi: 10.1007/s00269-016-0812-y

Welch MD, Rumsey MS, Kleppe AK (2016) A naturally-occurring new lead-based halocuprate(I). Journal of Solid State Chemistry, 238 : 9 - 14. doi: 10.1016/j.jssc.2016.03.005

Welch MD, Kampf AR (2016) Stoichiometric partially-protonated states in hydroxide perovskites: the jeanbandyite enigma revisited. Mineralogical Magazine,

Welch MD, Pawley AR (2016) Structural systematics of Ge substitution in primitive pyroxenes. Physics and Chemistry of Minerals, 43 (3) : 161 - 169. doi: 10.1007/s00269-015-0784-3

Kossoff D, Welch MD, Hudson-edwards KA (2015) Scorodite precipitation in the presence of antimony. Chemical Geology, 406 : 1 - 9. doi: 10.1016/j.chemgeo.2015.04.013

Welch MD, Sciberras MJ, Leverett P, Williams PA, Schlueter J, Malcherek T, Downes PJ, Hibbs DE, Kampf AR (2016) Structural and compositional variations of basic Cu(II) chlorides in the herbertsmithite and gillardite structure field.. Mineralogical Magazine,

Mitchell RH, Welch MD, Kampf AR, Chakhmouradian AK, Spratt J (2015) Barrydawsonite-(Y), Na1.5CaY0.5Si3O9H: a new pyroxenoid of the pectolite–serandite group. Mineralogical Magazine, 79 (3) : 671 - 686. doi: 10.1180/minmag.2015.079.3.12

Pawley AR, Welch MD (2014) Further complexities of the 10 A phase revealed by infrared spectroscopy and X-ray diffraction. American Mineralogist, 99 (4) : 712 - 719. doi: 10.2138/am.2014.4685

Welch MD, Mitchell RH, Kampf AR, Chakhmouradian AR, Smith D, Carter M (2014) Crystal structure and topological affinities of magbasite, KBaFe3+Mg7Si8O22(OH)(2)F-6: a trellis structure related to amphibole and carpholite. MINERALOGICAL MAGAZINE, 78 (1) : 29 - 45. doi: 10.1180/minmag.2014.078.1.03

Welch MD, Sciberras MJ, Williams PA, Leverett P, Schlüter J, Malcherek T (2014) A temperature-induced reversible transformation between paratacamite and herbertsmithite. Physics and Chemistry of Minerals, 41 (1) : 33 - 48. doi: 10.1007/s00269-013-0621-5

Kampf AR, Sciberras MJ, Leverett P, Williams PA, Malcherek T, Schlueter J, Welch MD, Dini M, Molina DonosoAA (2013) Paratacamite-(Mg), Cu-3(Mg, Cu) Cl-2(OH)(6); a new substituted basic copper chloride mineral from Camerones, Chile. MINERALOGICAL MAGAZINE, 77 (8) : 3113 - 3124. doi: 10.1180/minmag.2013.077.8.06

Rumsey MS, Welch MD, Kampf AR, Spratt J (2013) Diegogattaite, Na2CaCu2Si8O20 center dot H2O: a new nanoporous copper sheet silicate from Wessels Mine, Kalahari Manganese Fields, Republic of South Africa. MINERALOGICAL MAGAZINE, 77 (8) : 3155 - 3162. doi: 10.1180/minmag.2013.077.8.09

Welch MD, Sciberras MJ, Leverett P, Williams PA, Hibbs DE, Downes PJ, Kampf AR (2013) Paratacamite-(Ni), Cu3(Ni,Cu)Cl2(OH)6: a new substituted basic copper chloride mineral from Western Australia. Australian Journal of Mineralogy, 17 (1) : 39 - 44.

Welch MD, Rumsey MS (2013) A new naturally-occurring nanoporous copper sheet–silicate with 6482 cages related to synthetic “CuSH” phases. Journal of Solid State Chemistry, 203 : 260 - 265. doi: 10.1016/j.jssc.2013.04.019

Kleppe AK, Welch MD, Crichton WA, Jephcoat AP (2012) Phase transitions in hydroxide perovskites: a Raman spectroscopic study of stottite, FeGe(OH)6, to 21 GPa. Mineralogical Magazine, 76 (4) : 949 - 962. doi: 10.1180/minmag.2012.076.4.11

Nestola F, Pasqual D, Welch MD, Oberti R (2012) The effects of composition upon the high-pressure behaviour of amphiboles: compression of gedrite to 7 GPa and a comparison with anthophyllite and proto-amphibole. Mineralogical Magazine, 76 (4) : 987 - 995. doi: 10.1180/minmag.2012.076.4.14

Crichton WA, Parise JB, Müller H, Breger J, Marshall WG, Welch MD (2012) Synthesis and structure of magnesium hydroxide fluoride, Mg(OH)F: a topological intermediate between brucite- and rutile-type structures. Mineralogical Magazine, 76 (1) : 25 - 36. doi: 10.1180/minmag.2012.076.1.25

Hawthorne FC, Oberti R, Harlow GE, Maresch WV, Martin RF, Schumacher JC, Welch MD (2012) Nomenclature of the amphibole supergroup. American Mineralogist, 97 (11-12) : 2031 - 2048. doi: 10.2138/am.2012.4276

Welch MD, Konzett J, Bindi L, Kohn SC, Frost DJ (2012) New structural features of the high-pressure synthetic sheet-disilicate Phase-X, K(2-x)Mg2Si2O7Hx. American Mineralogist, 97 (11-12) : 1849 - 1857. doi: 10.2138/am.2012.4164

Welch MD, Wunder B (2012) A single-crystal X-ray diffraction study of the 3.65 Å-phase MgSi(OH)6, a high-pressure hydroxide perovskite. Physics and Chemistry of Minerals, 39 (9) : 693 - 697. doi: 10.1007/s00269-012-0523-y

Zema M, Welch MD, Oberti R (2012) High-T behaviour of gedrite: thermoelasticity, cation ordering and dehydrogenation. Contributions to Mineralogy and Petrology, 163 (5) : 923 - 937. doi: 10.1007/s00410-011-0706-4

Welch MD, Gatta GD, Rotiroti N (2011) The high-pressure behavior of orthorhombic amphiboles. American Mineralogist, 96 (4) : 623 - 630. doi: 10.2138/am.2011.3670

Welch MD, Cámara F, Oberti R (2011) Thermoelasticity and high-T behaviour of anthophyllite. Physics and Chemistry of Minerals, 38 : 321 - 334.

Welch MD, Montgomery W, Balan E, Lerch P (2011) Insights into the high-pressure behavior of kaolinite from infrared spectroscopy and quantum-mechanical calculations. Physics and Chemistry of Minerals, 30 : 143 - 151.

Lepore GO, Welch MD (2010) The crystal structure of parkinsonite, nominally Pb7MoO9Cl2: a naturally occurring Aurivillius phase. MINERALOGICAL MAGAZINE, 74 (2) : 269 - 275. doi: 10.1180/minmag.2010.074.2.269

Welch MD, Crichton WA (2010) Pressure-induced transformations in kaolinite. American Mineralogist, 95 (4) : 651 - 654. doi: 10.2138/am.2010.3408

Pawley AR, Welch MD, Lennie AR, Jones RL (2010) Volume behavior of the 10 A phase at high pressures and temperatures, with implications for H2O content. American Mineralogist, 95 (11-12) : 1671 - 1678. doi: 10.2138/am.2010.3526

Maresch WV, Welch MD, Gottschalk M, Ruthmann W, Czank M, Ashbrook SE (2009) Synthetic amphiboles and triple-chain silicates in the system Na2O–MgO–SiO2–H2O: phase characterization, compositional relations and excess H. Mineralogical Magazine, 73 (6) : 957 - 996. doi: 10.1180/minmag.2009.073.6.957

Müller A, Welch MD (2009) Frontiers in Quartz Research
Preface. Mineralogical Magazine, 73 (4) : 517 - 518. doi: 10.1180/minmag.2009.073.4.517

Yusupov RG, Stanley CJ, Welch MD, Spratt J, Cressey G, Rumsey MS, Seltmann R, Igamberdiev E (2009) Mavlyanovite, Mn5Si3: a new mineral species from a lamproite diatreme, Chatkal Ridge, Uzbekistan. Mineralogical Magazine, 73 (1) : 43 - 50. doi: 10.1180/minmag.2009.073.1.43

Hirai S, Welch MD, Aguado F, Redfern SAT (2009) The crystal structure of CaIrO3 post-perovskite revisited. Zeitschrift fur Kristallographie, 224 : 345 - 350.

Detrie TA, Ross NL, Angel RJ, Welch MD (2008) Crystal chemistry and location of hydrogen atoms in prehnite. Mineralogical Magazine, 72 (6) : 1163 - 1179. doi: 10.1180/minmag.2008.072.6.1163

Welch MD, Reece JJ, Redfern SAT (2008) Rapid intracrystalline exchange of octahedrally-coordinated divalent cations in amphiboles: an in situ high-temperature neutron diffraction study of synthetic potassic richterite K-A(B)(NaCa)(C)(Mg2.5Ni2.5)Si8O22(OH)(2). MINERALOGICAL MAGAZINE, 72 (4) : 877 - 886. doi: 10.1180/minmag.2008.072.4.877

Bindi L, Welch MD, Bonazzi P, Pratesi G, Menchetti S (2008) The crystal structure of seeligerite, Pb(3)IO(4)Cl(3), a rare Pb-I-oxychloride from the San Rafael mine, Sierra Gorda, Chile. MINERALOGICAL MAGAZINE, 72 (3) : 771 - 783. doi: 10.1180/minmag.2008.072.3.771

Yusupov RG, Stanley CJ, Welch MD, Spratt J, Cressey G, Rumsey MS, Seltmann R, Igamberdiev E (2008) Mavlyanovite, Mn5Si3, a new mineral. Geology and Mineral Resources, 5, 2008 : 3-6. [in Russian] - 3-6. [in Russian].

Dobson DP, De RondeAA, Welch MD, Meredith PG (2007) The acoustic emissions signature of a pressure-induced polytypic transformation in chlorite. American Mineralogist, 92 (2-3) : 437 - 440. doi: 10.2138/am.2007.2389

Welch MD, Camara F, Della VenturaG, Iezzi G (2007) Non-ambient in-situ studies of amphiboles.. MSA Reviews in Mineralogy & Geochemistry, 67 : 223 - 260.

Welch MD, Pawley AR, Ashbrook SE, Mason HE, Phillips BL (2006) Si vacancies in the 10-A phase. American Mineralogist, 91 (10) : 1707 - 1710. doi: 10.2138/am.2006.2319

Stanley CJ, Criddle AJ, Spratt J, Roberts AC, Szymanski JT, Welch MD (2005) Kingstonite, (Rh,Ir,Pt)(3)S-4, a new mineral species from Yubdo, Ethiopia. MINERALOGICAL MAGAZINE, 69 (4) : 447 - 453. doi: 10.1180/0026461056940262

Kleppe AK, Welch MD, Wright K (2005) Protons in minerals - Preface. MINERALOGICAL MAGAZINE, 69 (3) : 227 - 228.

Kleppe AK, Welch MD, Wright K (2005) Preface to the special issue: ‘Protons in Minerals’. Mineralogical Magazine, 69 : 227 - 228.

Mookherjee M, Welch MD, Le PollèsL, Redfern SAT, Harlov DE (2005) Ammonium ion behaviour in feldspar: variable-temperature infrared and 2H NMR studies of synthetic buddingtonite: N(D,H)4AlSi3O8. Physics and Chemistry of Minerals, 32 : 126 - 131.

Palin EJ, Dove MT, Welch MD, Redfern SAT (2005) Computational investigation of Al/Si and Al/Mg ordering in aluminous tremolite amphiboles. Mineralogical Magazine, 69 (1) : 1 - 20. doi: 10.1180/0026461056910232

Stanley CJ, Criddle AJ, Spratt J, Roberts AC, Szymański JT, Welch MD (2005) Kingstonite, (Rh,Ir,Pt)3S4, a new mineral species from Yubdo, Ethiopia. Mineralogical Magazine, 69 (4) : 447 - 454. doi: 10.1180/0026461056940262

Welch MD (2005) A high-pressure polytypic transformation in type-I chlorite. American Mineralogist, 90 (7) : 1139 - 1145. doi: 10.2138/am.2005.1756

Welch MD, Crichton WA, Ross NL (2005) Compression of the perovskite-related mineral bernalite Fe(OH)3 to 9 GPa and a reappraisal of its structure. Mineralogical Magazine, 69 (3) : 309 - 316. doi: 10.1180/0026461056930252

Welch MD (2005) Minerals: feldspathoids, In: Encyclopedia of Geology, Selley RC, COCKS LRM, Plimer IR (Eds). Elsevier Academic Press : 3200 pp. 539 - 541.

Camara F, Oberti R, Della VenturaG, Welch MD, Maresch WV (2004) The crystal-structure of synthetic NaNa2Mg5Si8O21(OH)(3), a triclinic C(1)over bar amphibole with a triple-cell and excess hydrogen. AMERICAN MINERALOGIST, 89 (10) : 1464 - 1473.

Welch MD (2004) Pb-Si ordering in sheet-oxychloride minerals: the super-structure of asisite, nominally Pb7SiO8Cl2. MINERALOGICAL MAGAZINE, 68 (2) : 247 - 254. doi: 10.1180/0026461046820185

Welch MD, Kleppe AK, Jephcoat AP (2004) Novel high-pressure behavior in chlorite: A synchrotron XRD study of clinochlore to 27 GPa. AMERICAN MINERALOGIST, 89 (8-9) : 1337 - 1340.

Kahl W-A, Maresch WV, Welch MD (2003) Enthalpy of formation of pargasite by high-temperature solution calorimetry and heat capacity of pargasite and fluoropargasite by differential scanning calorimetry. European Journal of Mineralogy, 15 (4) : 617 - 628. doi: 10.1127/0935-1221/2003/0015-0617

Kleppe AK, Jephcoat AP, Welch MD (2003) The effect of pressure upon hydrogen bonding in chlorite: A Raman spectroscopic study of clinochlore to 26.5 GPa. AMERICAN MINERALOGIST, 88 (4) : 567 - 573.

Navrotsky A, Xu HW, Moloy EC, Welch MD (2003) Thermochemistry of guest-free melanophlogite. AMERICAN MINERALOGIST, 88 (10) : 1612 - 1614.

Palin EJ, Guiton BS, Craig MS, Welch MD, Dove MT, Redfern SAT (2003) Computer simulation of Al-Mg ordering in glaucophane and a comparison with infrared spectroscopy. European Journal of Mineralogy, 15 (5) : 893 - 901. doi: 10.1127/0935-1221/2003/0015-0893

Welch MD, Lager GA (2003) Preface to the Hydrous Minerals at High Pressure Special Issue. American Mineralogist, 88 :

Ross NL, Chaplin TD, Welch MD (2002) Compressibility of stottite, FeGe(OH)(6): An octahedral framework with protonated O atoms. AMERICAN MINERALOGIST, 87 (10) : 1410 - 1414.

Welch MD, Crichton WA (2002) Compressibility to 7 GPa at 298 K of the protonated octahedral framework mineral burtite, CaSn(OH)6. Mineralogical Magazine, 66 (3) : 431 - 440. doi: 10.1180/0026461026630039

Welch MD, Crichton WA (2002) Compressibility of clinochlore to 8 GPa at 298 K and a comparison with micas. European Journal of Mineralogy, 14 (3) : 561 - 565. doi: 10.1127/0935-1221/2002/0014-0561

Welch MD, Marshall WG, Ross NL, Knight KS (2002) H positions in leucophoenicite, Mn7Si3O12(OH)(2): A close relative of the hydrous B phases. AMERICAN MINERALOGIST, 87 (1) : 154 - 159.

Le GodecY, Dove MT, Francis DJ, Kohn SC, Marshall WG, Pawley AR, Price GD, Redfern SAT, Rhodes N, Ross NL, Schofield PF, Schooneveld E, Syfosse G, Tucker MG, Welch MD (2001) Neutron diffraction at simultaneous high temperatures and pressures, with measurement of temperature by neutron radiography. Mineralogical Magazine, 65 (6) : 737 - 748. doi: 10.1180/0026461016560005

Welch MD, Cooper MA, Hawthorne FC (2001) The crystal structure of brunogeierite, Fe2GeO4 spinel. Mineralogical Magazine, 65 (3) : 441 - 444. doi: 10.1180/002646101300119529

Welch MD, Hawthorne FC, Cooper MA, Kyser TK (2001) TRIVALENT IODINE IN THE CRYSTAL STRUCTURE OF SCHWARTZEMBERGITE, Pb2+5 I3+ O6 H2 Cl3. The Canadian Mineralogist, 39 (3) : 785 - 795. doi: 10.2113/gscanmin.39.3.785

Welch MD, Marshall WG (2001) High-pressure behavior of clinochlore. AMERICAN MINERALOGIST, 86 (11-12) : 1380 - 1386.

Czank M, Welch MD, Liu S (2000) A 29 Si MAS-NMR study of Cd 7 [Ge 6 Si]O 21 pyroxmangite. Physics and Chemistry of Minerals, 27 (10) : 713 - 718. doi: 10.1007/s002690000115

Welch MD, Cooper MA, Hawthorne FC, Criddle AJ (2000) Symesite, Pb-10 (SO4) O7Cl4 (H2O), a new PbO-related sheet mineral: Description and crystal structure. AMERICAN MINERALOGIST, 85 (10) : 1526 - 1533.

Welch MD, Czank M, Liu S (2000) A 29Si MAS-NMR study of Cd7[Ge6Si]O21 pyroxmangite. Physics and Chemistry of Minerals, 27 : 713 - 718.

Reece JJ, Redfern SAT, Welch MD, Henderson CMB (2000) Mn-Mg disordering in cummingtonite: a high-temperature neutron powder diffraction study. Mineralogical Magazine, 64 (2) : 255 - 266. doi: 10.1180/002646100549166

Hawthorne FC, Welch MD, Della VentruaG, Liu SX, Robert JL, Jenkins DM (2000) Short-range order in synthetic aluminous tremolites: An infrared and triple-quantum MAS NMR study. AMERICAN MINERALOGIST, 85 (11-12) : 1716 - 1724.

Robert JL, Della VenturaG, Welch MD, Hawthorne FC (2000) The OH-F substitution in synthetic pargasite at 1.5 kbar, 850 degrees C. AMERICAN MINERALOGIST, 85 (7-8) : 926 - 931.

Yang Z, Cressey G, Welch M (1999) Reappraisal of the space group of bafertisite. Powder Diffraction, 14 (01) : 22 - 24. doi: 10.1017/S0885715600010253

Ventura GD, Hawthorne FC, Robert J-L, Delbove F, Welch MF, Raudsepp M (1999) Short-range order of cations in synthetic amphiboles along the richterite-pargasite join. European Journal of Mineralogy, 11 (1) : 79 - 94. doi: 10.1127/ejm/11/1/0079

Redfern SAT, Welch MD, Henderson CMB, Knight KS (1999) In situ high- t neutron diffraction studies of non-convergent order/disorder in minerals: From simple oxides to complex silicates. Phase Transitions 69 (1) : 17 - 34. doi: 10.1080/01411599908208005

Welch MD, Knight KS (1999) A neutron powder diffraction study of cation ordering in high-temperature synthetic amphiboles. EUROPEAN JOURNAL OF MINERALOGY, 11 (2) : 321 - 331.

Della VenturaG, Robert JL, Hawthorne FC, Raudsepp M, Welch MD (1998) Contrasting patterns of Al-[6] order in synthetic pargasite and Co-substituted pargasite. CANADIAN MINERALOGIST, 36 : 1237 - 1244.

Welch MD, Criddle AJ, Symes RF (1998) Mereheadite, Pb2O(OH)Cl: a new litharge-related oxychloride from Merehead Quarry, Cranmore, Somerset. Mineralogical Magazine, 62 (3) : 387 - 393. doi: 10.1180/002646198547657

Welch MD, Liu SX, Klinowski J (1998) Si-29 MAS NMR systematics of calcic and sodic-calcic amphiboles. AMERICAN MINERALOGIST, 83 (1-2) : 85 - 96.

Liu S, Welch MD, Klinowski J (1997) NMR Study of Phase Transitions in Guest-Free Silica Clathrate Melanophlogite. The Journal of Physical Chemistry B, 101 (15) : 2811 - 2814. doi: 10.1021/jp9638595

Delevoye L, Liu S, Welch MD, Fernandez C, Amoureux J-P, Klinowski J (1997) Triple-quantum 27Al and 23Na MAS NMR study of amphiboles. Journal of the Chemical Society, Faraday Transactions, 93 (15) : 2591 - 2595. doi: 10.1039/a701848g

Della VenturaG, Robert JL, Raudsepp M, Hawthorne FC, Welch MD (1997) Site occupancies in synthetic monoclinic amphiboles: Rietveld structure refinement and infrared spectroscopy of (nickel, magnesium, cobalt)-richterite. AMERICAN MINERALOGIST, 82 (3-4) : 291 - 301.

Hawthorne FC, Della VenturaG, Robert JL, Welch MD, Raudsepp M, Jenkins DM (1997) A Rietveld and infrared study of synthetic amphiboles along the potassium-richterite-tremolite join. AMERICAN MINERALOGIST, 82 (7-8) : 708 - 716.

Liu SX, Welch MD, Klinowski J, Maresch WV (1996) A MAS NMR study of a monoclinic/triclinic phase transition in an amphibole with excess OH:Na3Mg5Si8O21(OH)(3). EUROPEAN JOURNAL OF MINERALOGY, 8 (2) : 223 - 229.

Welch MD, Schofield PF, Cressey G, Stanley CJ (1996) Cation ordering in lead-molybdenum-vanadium oxychlorides. AMERICAN MINERALOGIST, 81 (11-12) : 1350 - 1359.

Welch MD, Barras J, Klinowski J (1995) A MULTINUCLEAR NMR-STUDY OF CLINOCHLORE. AMERICAN MINERALOGIST, 80 (5-6) : 441 - 447.

Welch MD, Kolodziejski W, Klinowski J (1995) A MULTINUCLEAR NMR-STUDY OF SYNTHETIC PARGASITE - REPLY. AMERICAN MINERALOGIST, 80 (5-6) : 629 - 629.

Welch MD, Kolodzjieski W, Klinowski J (1994) A multinuclear NMR study of pargasite. American Mineralogist, 79 : 261 - 268.

Welch M, Rocha JO, Klinowski J (1992) Characterization of polysomatism in biopyriboles: Double-/triple-chain lamellar intergrowths. Physics and Chemistry of Minerals, 18 (7) : doi: 10.1007/BF00200969

Graham CM, Welch MD (1992) An experimental study of glaucophanic amphiboles in the system Na2O-MgO-Al2O3- SiO2-SiF4 (NMASF): some implications for glaucophane stability in natural and synthetic systems at high temperatures and pressures. Contributions to Mineralogy and Petrology, 111 : 248 - 259.

Welch MD, Pawley AR (1991) Tremolite: new enthalpy and entropy data from a phase equilibrium study of the reaction Tremolite = 2 Diopside + 1.5 Orthoenstatite + β-Quartz + H2O.. American Mineralogist, 76 : 1931 - 1939.

Welch MD, Rocha J, Klinowski J (1991) 29Si MAS NMR magic-angle-spinning NMR spectroscopy quantitatively monitors the double-chain/triple-chain intergrowths in hydrous silicates. Journal of the American Chemical Society, 113 : 7100 - 7103.

Graham CM, Maresch WV, Welch MD, Pawley AR (1989) Experimental studies on amphiboles: a review with thermodynamic perspectives. European Journal of Mineralogy, 1 (4) : 535 - 556. doi: 10.1127/ejm/1/4/0535

Malcherek T, Mihailova B, Welch MD (2017) Structural phase transitions of clinoatacamite and the dynamic Jahn–Teller effect. Physics and Chemistry of Minerals, 44 (5) : 307 - 321. doi: 10.1007/s00269-016-0859-9

Courses taught

Second year: 1B Mineral Sciences: States of Order in Solids, the Role of Diffraction
University of Cambridge, Cambridge, Cambridge, United Kingdom
10/2000 - 6/2008.

Third year: Minerals Sciences Part 2: Mineral Behaviour
University of Cambridge, Cambridge, Cambridge, United Kingdom
10/1999 - 6/2008.

Course developed

Co developers: Welch MD
1B Mineral Sciences: States of Order in Solids, the Role of Diffraction, University of Cambridge, Cambridge, United Kingdom
9/10/2001

Introduction

Summary

I am a mineralogical crystallographer researching atomic-scale interactions that control the properties and transformational behaviour of minerals, with the aim of identifying and quantifying correlations between crystal structure, composition and mineral stability. Most of the materials that I research are structurally and chemically challenging and require use of a wide range of advanced diffraction and spectroscopic techniques including X-ray diffraction (XRD), neutron diffraction, MAS NMR, Raman and IR spectroscopies. Although I have used all of these methods extensively, my main technique is single-crystal XRD, using the NHM’s Xcalibur diffractometer housed in the Earth Sciences department. These studies include in situ experiments at variable temperature (to 1400 K) and pressure (to 20 GPa), aimed at understanding the behaviour of minerals at conditions of the Earth’s crust and mantle, particularly in subduction zones, and the implications this behaviour has for mantle processes. I have two main research fields: (i) Hydrous minerals in the Earth’s crust and mantle, and (ii) new-to-science and associated novel technology-related minerals. _________________________________________________________________________________ HYDROUS MINERALS AND THE DEEP MANTLE. A major component of my research relates to quantifying and rationalising the crystal chemistry of geologically important hydrous phases, their protonation phenomena and physical properties relevant to understanding their roles as agents of water transfer into the deep mantle (>200 km) at subduction zones. These hydrous phases include amphibole, chlorite, talc, 10Å -phase, MgSi(OH)6 perovskite and hydrous phase-X K1.5Mg2Si2O7H0.5. Recent advances relate to identifying protonation mechanisms in 10A-phase and the origin of large superstructures coupled to H and K ordering in Phase-X. My work on talc and 10Å-phase demonstrated how the hydrophobic sheet of talc becomes highly hydrophilic by the creation of Si vacancies via SiO4 = (OH)4 and how this modification is central to understanding the stability of 10Å-phase at high pressure and how significantly more water can be taken up by sheet silicates with increasing pressure. In 2007 I was elected a Fellow of the Mineralogical Society of America in recognition of my contributions to understanding the crystal chemistry, thermodynamics and physical properties of geologically important hydrous minerals (amphiboles, sheet silicates, hydroxides). __________________________________________________________________________________ MINERALS NEW TO SCIENCE. I have been involved in the structural characterisation of 17 new-to-science minerals. Most of these minerals have completely new structure topologies, no synthetic analogues and several are related to technologically-significant compounds associated with catalysis, optoelectronics, ionic conduction and frustrated antiferromagnets (Kagome phases). I have served twice (2003-2007 and 2010-2015) on the International Mineralogical Association’s Commission on New Minerals, Nomenclature and Classification, which evaluates over 120 new minerals each year. My recent research on new minerals of the atacamite group, closely-related to the classic frustrated antiferromagnets herbertsmithite Cu3Zn(OH)6Cl2 and tondiite Cu3Mg(OH)6Cl2, has identified new transitional behaviour (dynamic Jahn-Teller distortion) and quantified the effects of small degrees of solid solution upon these transitions. Such information bears on understanding how doping of synthetic herbertsmithites can be used to understand the magnetic properties of this technologically-important group of minerals. __________________________________________________________________________________ I have been associate editor and chief editor for long-established international peer-reviewed journals, including American Mineralogist and Mineralogical Magazine (Chief Editor 2006-2011). I have served on numerous international committees, including Mineralogical Society of America (MSA Award, Public Service Award), Mineralogical Society of Great Britain & Ireland (Officer, Council), IMA (Council), IMA (CNMNC), IMA Medal committee and the International Union of Crystallography (Inorganic Crystal Structures Commission).

Qualifications

Degrees

PhD, University of Edinburgh, Edinburgh

Employment history

Academic

Researcher in Mineral Sciences,, Natural History Museum, Earth Sciences, United Kingdom, 1992 - ongoing

Associate Lecturer in Mineral Sciences, University of Cambridge, Earth Sciences, United Kingdom, 1999 - 2008

NERC Special Fellow & University of Cambridge Research Fellow, University of Cambridge, Earth Sciences, United Kingdom, 1989 - 1992

NERC Post-doctoral Research Fellow, University of Edinburgh, Geosciences, United Kingdom, 1987 - 1989

Highlighted publications

Welch MD, Bindi L, Petříček V, Plášil J (2016) Vacancy pairing and superstructure in the high-pressure silicate K 1.5 Mg 2 Si 2 O 7 H 0.5 : a new potential host for potassium in the deep Earth. Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials, 72 (6) : 822 - 827. doi: 10.1107/S2052520616014049

Welch MD, Rumsey MS, Kleppe AK (2016) A naturally-occurring new lead-based halocuprate(I). Journal of Solid State Chemistry, 238 : 9 - 14. doi: 10.1016/j.jssc.2016.03.005

Welch MD, Rumsey MS (2013) A new naturally-occurring nanoporous copper sheet–silicate with 6482 cages related to synthetic “CuSH” phases. Journal of Solid State Chemistry, 203 : 260 - 265. doi: 10.1016/j.jssc.2013.04.019

Hawthorne FC, Oberti R, Harlow GE, Maresch WV, Martin RF, et al. (2012) Nomenclature of the amphibole supergroup. American Mineralogist, 97 (11-12) : 2031 - 2048. doi: 10.2138/am.2012.4276

Welch MD, Camara F, Della VenturaG, Iezzi G (2007) Non-ambient in-situ studies of amphiboles.. MSA Reviews in Mineralogy & Geochemistry, 67 : 223 - 260.

Welch MD, Pawley AR, Ashbrook SE, Mason HE, Phillips BL (2006) Si vacancies in the 10-A phase. American Mineralogist, 91 (10) : 1707 - 1710. doi: 10.2138/am.2006.2319

Professional activities

Fellowships

Fellow of the Mineralogical Society of America, 2007 - on going.

Fellow, Selwyn College, University of Cambridge, 1989 - 1993.

University of Cambridge Research Fellowship, 1989 - 1992.

NERC Special Fellowship, University of Cambridge, University of Cambridge, Cambridge, Cambridge, United Kingdom, 1989 - 1992.

NERC postdoctoral research fellowship, University of Edinburgh, University of Edinburgh, Edinburgh, Edinburgh, United Kingdom, 1987 - 1989.

Committees

Member, Mineralogical Society of America Public Service Award, 2017 - on going.

Member, International Union for Crystallography Commission on Inorganic Structures, 2016 - on going.

Member, Mineralogical Society of America Award, Mineralogical Society of America, Chantilly, United States, 2014 - 2016.

Member, IMA Commission on New Minerals, Nomenclature & Classification, 2013 - on going.

Member, IMA Commission on New Minerals, Nomenclature & Classification, 2003 - 2007.

Editorships

Editor in chief, Mineralogical Magazine, Mineralogical Society of Great Britain & Ireland, 2006 - 2011.

Guest Editor, American Mineralogist, Mineralogical Society of America, 2004 - 2004.

Associate editor, Mineralogical Magazine, Mineralogical Society of Great Britain and Ireland, 2001 - 2004.

Associate editor, American Mineralogist, Mineralogical Society of America, 1999 - 2003.

Publications

Publications

Welch M, Still JW, Rice CM, Stanley CJ (2017) A new telluride topology: the crystal structure of honeaite Au 3 TlTe 2. Mineralogical Magazine, 81 (3) : 611 - 618. doi: 10.1180/minmag.2016.080.112

Mitchell R, Welch M, Chakhmouradian A (2017) Nomenclature of the perovskite supergroup: A hierarchical system of classification based on crystal structure and composition. Mineralogical Magazine, 81 (3) : 411 - 461. doi: 10.1180/minmag.2016.080.156

Rice C, Welch M, Still J, Criddle A, Stanley C (2016) Honeaite, a new gold-thallium-telluride from the Eastern Goldfields, Yilgarn Craton, Western Australia. European Journal of Mineralogy, 28 (5) : 979 - 990. doi: 10.1127/ejm/2016/0028-2559

Welch MD, Bindi L, Petříček V, Plášil J (2016) Vacancy pairing and superstructure in the high-pressure silicate K 1.5 Mg 2 Si 2 O 7 H 0.5 : a new potential host for potassium in the deep Earth. Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials, 72 (6) : 822 - 827. doi: 10.1107/S2052520616014049

Welch MD, Kleppe AK (2016) Polymorphism of the hydroxide perovskite Ga(OH)3 and possible proton-driven transformational behaviour. Physics and Chemistry of Minerals, 43 (7) : 515 - 526. doi: 10.1007/s00269-016-0812-y

Welch MD, Rumsey MS, Kleppe AK (2016) A naturally-occurring new lead-based halocuprate(I). Journal of Solid State Chemistry, 238 : 9 - 14. doi: 10.1016/j.jssc.2016.03.005

Welch MD, Kampf AR (2016) Stoichiometric partially-protonated states in hydroxide perovskites: the jeanbandyite enigma revisited. Mineralogical Magazine,

Welch MD, Pawley AR (2016) Structural systematics of Ge substitution in primitive pyroxenes. Physics and Chemistry of Minerals, 43 (3) : 161 - 169. doi: 10.1007/s00269-015-0784-3

Kossoff D, Welch MD, Hudson-edwards KA (2015) Scorodite precipitation in the presence of antimony. Chemical Geology, 406 : 1 - 9. doi: 10.1016/j.chemgeo.2015.04.013

Welch MD, Sciberras MJ, Leverett P, Williams PA, Schlueter J, Malcherek T, Downes PJ, Hibbs DE, Kampf AR (2016) Structural and compositional variations of basic Cu(II) chlorides in the herbertsmithite and gillardite structure field.. Mineralogical Magazine,

Mitchell RH, Welch MD, Kampf AR, Chakhmouradian AK, Spratt J (2015) Barrydawsonite-(Y), Na1.5CaY0.5Si3O9H: a new pyroxenoid of the pectolite–serandite group. Mineralogical Magazine, 79 (3) : 671 - 686. doi: 10.1180/minmag.2015.079.3.12

Pawley AR, Welch MD (2014) Further complexities of the 10 A phase revealed by infrared spectroscopy and X-ray diffraction. American Mineralogist, 99 (4) : 712 - 719. doi: 10.2138/am.2014.4685

Welch MD, Mitchell RH, Kampf AR, Chakhmouradian AR, Smith D, Carter M (2014) Crystal structure and topological affinities of magbasite, KBaFe3+Mg7Si8O22(OH)(2)F-6: a trellis structure related to amphibole and carpholite. MINERALOGICAL MAGAZINE, 78 (1) : 29 - 45. doi: 10.1180/minmag.2014.078.1.03

Welch MD, Sciberras MJ, Williams PA, Leverett P, Schlüter J, Malcherek T (2014) A temperature-induced reversible transformation between paratacamite and herbertsmithite. Physics and Chemistry of Minerals, 41 (1) : 33 - 48. doi: 10.1007/s00269-013-0621-5

Kampf AR, Sciberras MJ, Leverett P, Williams PA, Malcherek T, Schlueter J, Welch MD, Dini M, Molina DonosoAA (2013) Paratacamite-(Mg), Cu-3(Mg, Cu) Cl-2(OH)(6); a new substituted basic copper chloride mineral from Camerones, Chile. MINERALOGICAL MAGAZINE, 77 (8) : 3113 - 3124. doi: 10.1180/minmag.2013.077.8.06

Rumsey MS, Welch MD, Kampf AR, Spratt J (2013) Diegogattaite, Na2CaCu2Si8O20 center dot H2O: a new nanoporous copper sheet silicate from Wessels Mine, Kalahari Manganese Fields, Republic of South Africa. MINERALOGICAL MAGAZINE, 77 (8) : 3155 - 3162. doi: 10.1180/minmag.2013.077.8.09

Welch MD, Sciberras MJ, Leverett P, Williams PA, Hibbs DE, Downes PJ, Kampf AR (2013) Paratacamite-(Ni), Cu3(Ni,Cu)Cl2(OH)6: a new substituted basic copper chloride mineral from Western Australia. Australian Journal of Mineralogy, 17 (1) : 39 - 44.

Welch MD, Rumsey MS (2013) A new naturally-occurring nanoporous copper sheet–silicate with 6482 cages related to synthetic “CuSH” phases. Journal of Solid State Chemistry, 203 : 260 - 265. doi: 10.1016/j.jssc.2013.04.019

Kleppe AK, Welch MD, Crichton WA, Jephcoat AP (2012) Phase transitions in hydroxide perovskites: a Raman spectroscopic study of stottite, FeGe(OH)6, to 21 GPa. Mineralogical Magazine, 76 (4) : 949 - 962. doi: 10.1180/minmag.2012.076.4.11

Nestola F, Pasqual D, Welch MD, Oberti R (2012) The effects of composition upon the high-pressure behaviour of amphiboles: compression of gedrite to 7 GPa and a comparison with anthophyllite and proto-amphibole. Mineralogical Magazine, 76 (4) : 987 - 995. doi: 10.1180/minmag.2012.076.4.14

Crichton WA, Parise JB, Müller H, Breger J, Marshall WG, Welch MD (2012) Synthesis and structure of magnesium hydroxide fluoride, Mg(OH)F: a topological intermediate between brucite- and rutile-type structures. Mineralogical Magazine, 76 (1) : 25 - 36. doi: 10.1180/minmag.2012.076.1.25

Hawthorne FC, Oberti R, Harlow GE, Maresch WV, Martin RF, Schumacher JC, Welch MD (2012) Nomenclature of the amphibole supergroup. American Mineralogist, 97 (11-12) : 2031 - 2048. doi: 10.2138/am.2012.4276

Welch MD, Konzett J, Bindi L, Kohn SC, Frost DJ (2012) New structural features of the high-pressure synthetic sheet-disilicate Phase-X, K(2-x)Mg2Si2O7Hx. American Mineralogist, 97 (11-12) : 1849 - 1857. doi: 10.2138/am.2012.4164

Welch MD, Wunder B (2012) A single-crystal X-ray diffraction study of the 3.65 Å-phase MgSi(OH)6, a high-pressure hydroxide perovskite. Physics and Chemistry of Minerals, 39 (9) : 693 - 697. doi: 10.1007/s00269-012-0523-y

Zema M, Welch MD, Oberti R (2012) High-T behaviour of gedrite: thermoelasticity, cation ordering and dehydrogenation. Contributions to Mineralogy and Petrology, 163 (5) : 923 - 937. doi: 10.1007/s00410-011-0706-4

Welch MD, Gatta GD, Rotiroti N (2011) The high-pressure behavior of orthorhombic amphiboles. American Mineralogist, 96 (4) : 623 - 630. doi: 10.2138/am.2011.3670

Welch MD, Cámara F, Oberti R (2011) Thermoelasticity and high-T behaviour of anthophyllite. Physics and Chemistry of Minerals, 38 : 321 - 334.

Welch MD, Montgomery W, Balan E, Lerch P (2011) Insights into the high-pressure behavior of kaolinite from infrared spectroscopy and quantum-mechanical calculations. Physics and Chemistry of Minerals, 30 : 143 - 151.

Lepore GO, Welch MD (2010) The crystal structure of parkinsonite, nominally Pb7MoO9Cl2: a naturally occurring Aurivillius phase. MINERALOGICAL MAGAZINE, 74 (2) : 269 - 275. doi: 10.1180/minmag.2010.074.2.269

Welch MD, Crichton WA (2010) Pressure-induced transformations in kaolinite. American Mineralogist, 95 (4) : 651 - 654. doi: 10.2138/am.2010.3408

Pawley AR, Welch MD, Lennie AR, Jones RL (2010) Volume behavior of the 10 A phase at high pressures and temperatures, with implications for H2O content. American Mineralogist, 95 (11-12) : 1671 - 1678. doi: 10.2138/am.2010.3526

Maresch WV, Welch MD, Gottschalk M, Ruthmann W, Czank M, Ashbrook SE (2009) Synthetic amphiboles and triple-chain silicates in the system Na2O–MgO–SiO2–H2O: phase characterization, compositional relations and excess H. Mineralogical Magazine, 73 (6) : 957 - 996. doi: 10.1180/minmag.2009.073.6.957

Müller A, Welch MD (2009) Frontiers in Quartz Research
Preface. Mineralogical Magazine, 73 (4) : 517 - 518. doi: 10.1180/minmag.2009.073.4.517

Yusupov RG, Stanley CJ, Welch MD, Spratt J, Cressey G, Rumsey MS, Seltmann R, Igamberdiev E (2009) Mavlyanovite, Mn5Si3: a new mineral species from a lamproite diatreme, Chatkal Ridge, Uzbekistan. Mineralogical Magazine, 73 (1) : 43 - 50. doi: 10.1180/minmag.2009.073.1.43

Hirai S, Welch MD, Aguado F, Redfern SAT (2009) The crystal structure of CaIrO3 post-perovskite revisited. Zeitschrift fur Kristallographie, 224 : 345 - 350.

Detrie TA, Ross NL, Angel RJ, Welch MD (2008) Crystal chemistry and location of hydrogen atoms in prehnite. Mineralogical Magazine, 72 (6) : 1163 - 1179. doi: 10.1180/minmag.2008.072.6.1163

Welch MD, Reece JJ, Redfern SAT (2008) Rapid intracrystalline exchange of octahedrally-coordinated divalent cations in amphiboles: an in situ high-temperature neutron diffraction study of synthetic potassic richterite K-A(B)(NaCa)(C)(Mg2.5Ni2.5)Si8O22(OH)(2). MINERALOGICAL MAGAZINE, 72 (4) : 877 - 886. doi: 10.1180/minmag.2008.072.4.877

Bindi L, Welch MD, Bonazzi P, Pratesi G, Menchetti S (2008) The crystal structure of seeligerite, Pb(3)IO(4)Cl(3), a rare Pb-I-oxychloride from the San Rafael mine, Sierra Gorda, Chile. MINERALOGICAL MAGAZINE, 72 (3) : 771 - 783. doi: 10.1180/minmag.2008.072.3.771

Yusupov RG, Stanley CJ, Welch MD, Spratt J, Cressey G, Rumsey MS, Seltmann R, Igamberdiev E (2008) Mavlyanovite, Mn5Si3, a new mineral. Geology and Mineral Resources, 5, 2008 : 3-6. [in Russian] - 3-6. [in Russian].

Dobson DP, De RondeAA, Welch MD, Meredith PG (2007) The acoustic emissions signature of a pressure-induced polytypic transformation in chlorite. American Mineralogist, 92 (2-3) : 437 - 440. doi: 10.2138/am.2007.2389

Welch MD, Camara F, Della VenturaG, Iezzi G (2007) Non-ambient in-situ studies of amphiboles.. MSA Reviews in Mineralogy & Geochemistry, 67 : 223 - 260.

Welch MD, Pawley AR, Ashbrook SE, Mason HE, Phillips BL (2006) Si vacancies in the 10-A phase. American Mineralogist, 91 (10) : 1707 - 1710. doi: 10.2138/am.2006.2319

Stanley CJ, Criddle AJ, Spratt J, Roberts AC, Szymanski JT, Welch MD (2005) Kingstonite, (Rh,Ir,Pt)(3)S-4, a new mineral species from Yubdo, Ethiopia. MINERALOGICAL MAGAZINE, 69 (4) : 447 - 453. doi: 10.1180/0026461056940262

Kleppe AK, Welch MD, Wright K (2005) Protons in minerals - Preface. MINERALOGICAL MAGAZINE, 69 (3) : 227 - 228.

Kleppe AK, Welch MD, Wright K (2005) Preface to the special issue: ‘Protons in Minerals’. Mineralogical Magazine, 69 : 227 - 228.

Mookherjee M, Welch MD, Le PollèsL, Redfern SAT, Harlov DE (2005) Ammonium ion behaviour in feldspar: variable-temperature infrared and 2H NMR studies of synthetic buddingtonite: N(D,H)4AlSi3O8. Physics and Chemistry of Minerals, 32 : 126 - 131.

Palin EJ, Dove MT, Welch MD, Redfern SAT (2005) Computational investigation of Al/Si and Al/Mg ordering in aluminous tremolite amphiboles. Mineralogical Magazine, 69 (1) : 1 - 20. doi: 10.1180/0026461056910232

Stanley CJ, Criddle AJ, Spratt J, Roberts AC, Szymański JT, Welch MD (2005) Kingstonite, (Rh,Ir,Pt)3S4, a new mineral species from Yubdo, Ethiopia. Mineralogical Magazine, 69 (4) : 447 - 454. doi: 10.1180/0026461056940262

Welch MD (2005) A high-pressure polytypic transformation in type-I chlorite. American Mineralogist, 90 (7) : 1139 - 1145. doi: 10.2138/am.2005.1756

Welch MD, Crichton WA, Ross NL (2005) Compression of the perovskite-related mineral bernalite Fe(OH)3 to 9 GPa and a reappraisal of its structure. Mineralogical Magazine, 69 (3) : 309 - 316. doi: 10.1180/0026461056930252

Welch MD (2005) Minerals: feldspathoids, In: Encyclopedia of Geology, Selley RC, COCKS LRM, Plimer IR (Eds). Elsevier Academic Press : 3200 pp. 539 - 541.

Camara F, Oberti R, Della VenturaG, Welch MD, Maresch WV (2004) The crystal-structure of synthetic NaNa2Mg5Si8O21(OH)(3), a triclinic C(1)over bar amphibole with a triple-cell and excess hydrogen. AMERICAN MINERALOGIST, 89 (10) : 1464 - 1473.

Welch MD (2004) Pb-Si ordering in sheet-oxychloride minerals: the super-structure of asisite, nominally Pb7SiO8Cl2. MINERALOGICAL MAGAZINE, 68 (2) : 247 - 254. doi: 10.1180/0026461046820185

Welch MD, Kleppe AK, Jephcoat AP (2004) Novel high-pressure behavior in chlorite: A synchrotron XRD study of clinochlore to 27 GPa. AMERICAN MINERALOGIST, 89 (8-9) : 1337 - 1340.

Kahl W-A, Maresch WV, Welch MD (2003) Enthalpy of formation of pargasite by high-temperature solution calorimetry and heat capacity of pargasite and fluoropargasite by differential scanning calorimetry. European Journal of Mineralogy, 15 (4) : 617 - 628. doi: 10.1127/0935-1221/2003/0015-0617

Kleppe AK, Jephcoat AP, Welch MD (2003) The effect of pressure upon hydrogen bonding in chlorite: A Raman spectroscopic study of clinochlore to 26.5 GPa. AMERICAN MINERALOGIST, 88 (4) : 567 - 573.

Navrotsky A, Xu HW, Moloy EC, Welch MD (2003) Thermochemistry of guest-free melanophlogite. AMERICAN MINERALOGIST, 88 (10) : 1612 - 1614.

Palin EJ, Guiton BS, Craig MS, Welch MD, Dove MT, Redfern SAT (2003) Computer simulation of Al-Mg ordering in glaucophane and a comparison with infrared spectroscopy. European Journal of Mineralogy, 15 (5) : 893 - 901. doi: 10.1127/0935-1221/2003/0015-0893

Welch MD, Lager GA (2003) Preface to the Hydrous Minerals at High Pressure Special Issue. American Mineralogist, 88 :

Ross NL, Chaplin TD, Welch MD (2002) Compressibility of stottite, FeGe(OH)(6): An octahedral framework with protonated O atoms. AMERICAN MINERALOGIST, 87 (10) : 1410 - 1414.

Welch MD, Crichton WA (2002) Compressibility to 7 GPa at 298 K of the protonated octahedral framework mineral burtite, CaSn(OH)6. Mineralogical Magazine, 66 (3) : 431 - 440. doi: 10.1180/0026461026630039

Welch MD, Crichton WA (2002) Compressibility of clinochlore to 8 GPa at 298 K and a comparison with micas. European Journal of Mineralogy, 14 (3) : 561 - 565. doi: 10.1127/0935-1221/2002/0014-0561

Welch MD, Marshall WG, Ross NL, Knight KS (2002) H positions in leucophoenicite, Mn7Si3O12(OH)(2): A close relative of the hydrous B phases. AMERICAN MINERALOGIST, 87 (1) : 154 - 159.

Le GodecY, Dove MT, Francis DJ, Kohn SC, Marshall WG, Pawley AR, Price GD, Redfern SAT, Rhodes N, Ross NL, Schofield PF, Schooneveld E, Syfosse G, Tucker MG, Welch MD (2001) Neutron diffraction at simultaneous high temperatures and pressures, with measurement of temperature by neutron radiography. Mineralogical Magazine, 65 (6) : 737 - 748. doi: 10.1180/0026461016560005

Welch MD, Cooper MA, Hawthorne FC (2001) The crystal structure of brunogeierite, Fe2GeO4 spinel. Mineralogical Magazine, 65 (3) : 441 - 444. doi: 10.1180/002646101300119529

Welch MD, Hawthorne FC, Cooper MA, Kyser TK (2001) TRIVALENT IODINE IN THE CRYSTAL STRUCTURE OF SCHWARTZEMBERGITE, Pb2+5 I3+ O6 H2 Cl3. The Canadian Mineralogist, 39 (3) : 785 - 795. doi: 10.2113/gscanmin.39.3.785

Welch MD, Marshall WG (2001) High-pressure behavior of clinochlore. AMERICAN MINERALOGIST, 86 (11-12) : 1380 - 1386.

Czank M, Welch MD, Liu S (2000) A 29 Si MAS-NMR study of Cd 7 [Ge 6 Si]O 21 pyroxmangite. Physics and Chemistry of Minerals, 27 (10) : 713 - 718. doi: 10.1007/s002690000115

Welch MD, Cooper MA, Hawthorne FC, Criddle AJ (2000) Symesite, Pb-10 (SO4) O7Cl4 (H2O), a new PbO-related sheet mineral: Description and crystal structure. AMERICAN MINERALOGIST, 85 (10) : 1526 - 1533.

Welch MD, Czank M, Liu S (2000) A 29Si MAS-NMR study of Cd7[Ge6Si]O21 pyroxmangite. Physics and Chemistry of Minerals, 27 : 713 - 718.

Reece JJ, Redfern SAT, Welch MD, Henderson CMB (2000) Mn-Mg disordering in cummingtonite: a high-temperature neutron powder diffraction study. Mineralogical Magazine, 64 (2) : 255 - 266. doi: 10.1180/002646100549166

Hawthorne FC, Welch MD, Della VentruaG, Liu SX, Robert JL, Jenkins DM (2000) Short-range order in synthetic aluminous tremolites: An infrared and triple-quantum MAS NMR study. AMERICAN MINERALOGIST, 85 (11-12) : 1716 - 1724.

Robert JL, Della VenturaG, Welch MD, Hawthorne FC (2000) The OH-F substitution in synthetic pargasite at 1.5 kbar, 850 degrees C. AMERICAN MINERALOGIST, 85 (7-8) : 926 - 931.

Yang Z, Cressey G, Welch M (1999) Reappraisal of the space group of bafertisite. Powder Diffraction, 14 (01) : 22 - 24. doi: 10.1017/S0885715600010253

Ventura GD, Hawthorne FC, Robert J-L, Delbove F, Welch MF, Raudsepp M (1999) Short-range order of cations in synthetic amphiboles along the richterite-pargasite join. European Journal of Mineralogy, 11 (1) : 79 - 94. doi: 10.1127/ejm/11/1/0079

Redfern SAT, Welch MD, Henderson CMB, Knight KS (1999) In situ high- t neutron diffraction studies of non-convergent order/disorder in minerals: From simple oxides to complex silicates. Phase Transitions 69 (1) : 17 - 34. doi: 10.1080/01411599908208005

Welch MD, Knight KS (1999) A neutron powder diffraction study of cation ordering in high-temperature synthetic amphiboles. EUROPEAN JOURNAL OF MINERALOGY, 11 (2) : 321 - 331.

Della VenturaG, Robert JL, Hawthorne FC, Raudsepp M, Welch MD (1998) Contrasting patterns of Al-[6] order in synthetic pargasite and Co-substituted pargasite. CANADIAN MINERALOGIST, 36 : 1237 - 1244.

Welch MD, Criddle AJ, Symes RF (1998) Mereheadite, Pb2O(OH)Cl: a new litharge-related oxychloride from Merehead Quarry, Cranmore, Somerset. Mineralogical Magazine, 62 (3) : 387 - 393. doi: 10.1180/002646198547657

Welch MD, Liu SX, Klinowski J (1998) Si-29 MAS NMR systematics of calcic and sodic-calcic amphiboles. AMERICAN MINERALOGIST, 83 (1-2) : 85 - 96.

Liu S, Welch MD, Klinowski J (1997) NMR Study of Phase Transitions in Guest-Free Silica Clathrate Melanophlogite. The Journal of Physical Chemistry B, 101 (15) : 2811 - 2814. doi: 10.1021/jp9638595

Delevoye L, Liu S, Welch MD, Fernandez C, Amoureux J-P, Klinowski J (1997) Triple-quantum 27Al and 23Na MAS NMR study of amphiboles. Journal of the Chemical Society, Faraday Transactions, 93 (15) : 2591 - 2595. doi: 10.1039/a701848g

Della VenturaG, Robert JL, Raudsepp M, Hawthorne FC, Welch MD (1997) Site occupancies in synthetic monoclinic amphiboles: Rietveld structure refinement and infrared spectroscopy of (nickel, magnesium, cobalt)-richterite. AMERICAN MINERALOGIST, 82 (3-4) : 291 - 301.

Hawthorne FC, Della VenturaG, Robert JL, Welch MD, Raudsepp M, Jenkins DM (1997) A Rietveld and infrared study of synthetic amphiboles along the potassium-richterite-tremolite join. AMERICAN MINERALOGIST, 82 (7-8) : 708 - 716.

Liu SX, Welch MD, Klinowski J, Maresch WV (1996) A MAS NMR study of a monoclinic/triclinic phase transition in an amphibole with excess OH:Na3Mg5Si8O21(OH)(3). EUROPEAN JOURNAL OF MINERALOGY, 8 (2) : 223 - 229.

Welch MD, Schofield PF, Cressey G, Stanley CJ (1996) Cation ordering in lead-molybdenum-vanadium oxychlorides. AMERICAN MINERALOGIST, 81 (11-12) : 1350 - 1359.

Welch MD, Barras J, Klinowski J (1995) A MULTINUCLEAR NMR-STUDY OF CLINOCHLORE. AMERICAN MINERALOGIST, 80 (5-6) : 441 - 447.

Welch MD, Kolodziejski W, Klinowski J (1995) A MULTINUCLEAR NMR-STUDY OF SYNTHETIC PARGASITE - REPLY. AMERICAN MINERALOGIST, 80 (5-6) : 629 - 629.

Welch MD, Kolodzjieski W, Klinowski J (1994) A multinuclear NMR study of pargasite. American Mineralogist, 79 : 261 - 268.

Welch M, Rocha JO, Klinowski J (1992) Characterization of polysomatism in biopyriboles: Double-/triple-chain lamellar intergrowths. Physics and Chemistry of Minerals, 18 (7) : doi: 10.1007/BF00200969

Graham CM, Welch MD (1992) An experimental study of glaucophanic amphiboles in the system Na2O-MgO-Al2O3- SiO2-SiF4 (NMASF): some implications for glaucophane stability in natural and synthetic systems at high temperatures and pressures. Contributions to Mineralogy and Petrology, 111 : 248 - 259.

Welch MD, Pawley AR (1991) Tremolite: new enthalpy and entropy data from a phase equilibrium study of the reaction Tremolite = 2 Diopside + 1.5 Orthoenstatite + β-Quartz + H2O.. American Mineralogist, 76 : 1931 - 1939.

Welch MD, Rocha J, Klinowski J (1991) 29Si MAS NMR magic-angle-spinning NMR spectroscopy quantitatively monitors the double-chain/triple-chain intergrowths in hydrous silicates. Journal of the American Chemical Society, 113 : 7100 - 7103.

Graham CM, Maresch WV, Welch MD, Pawley AR (1989) Experimental studies on amphiboles: a review with thermodynamic perspectives. European Journal of Mineralogy, 1 (4) : 535 - 556. doi: 10.1127/ejm/1/4/0535

Malcherek T, Mihailova B, Welch MD (2017) Structural phase transitions of clinoatacamite and the dynamic Jahn–Teller effect. Physics and Chemistry of Minerals, 44 (5) : 307 - 321. doi: 10.1007/s00269-016-0859-9

Teaching and students

Courses taught

Second year: 1B Mineral Sciences: States of Order in Solids, the Role of Diffraction
University of Cambridge, Cambridge, Cambridge, United Kingdom
10/2000 - 6/2008.

Third year: Minerals Sciences Part 2: Mineral Behaviour
University of Cambridge, Cambridge, Cambridge, United Kingdom
10/1999 - 6/2008.

Course developed

Co developers: Welch MD
1B Mineral Sciences: States of Order in Solids, the Role of Diffraction, University of Cambridge, Cambridge, United Kingdom
9/10/2001