The first photo shows cubic crystals that I think could be goethite ((FeO(OH)) replacements of cubic iron pryite crystals (called goethite pseudomorphs after pyrite) or else a superficial coating of goethite upon pyrite (FeS2) crystals. I've attached a fact sheet that gives more information about pyrite. Cubic pyrite crystals are common and often become replaced or coated by by goethite.
The second photo also possibly shows some kind of iron oxide, hydroxide or sulphide ore.
The third photo most likely shows a purple variety of quartz that could be termed amethyst (although this term is sometimes reserved for purple quartz of higher quality).
It's very difficult to identify minerals from photos alone as so much information such as the hardness, density, streak is lost and even visual information such as tiny mineral faces and cleavage are hard to discern. Please do pipe up if you have any other suggestions! Hope this helps a bit.