Cathodoluminescence images

The Zeiss EVO 15LS scanning electron microscope's cathodoluminescence detector can be used to create images from light emitted by a sample. These can provide information about the internal structure of crystals and can be used to construct histories of mineral deposition and crystal growth for a variety of purposes. Read about some examples below.

Backscattered electron and cathodoluminescence images of a polished section of volcanic rock

Cathodoluminescence montages of ore-bearing quartz veins can be used to understand the history of mineral deposition in metallic ore bodies.

Whereas the top backscattered electron image of a polished section of volcanic rock shows a large area of quartz set in impregnating resin, it does not show any internal structure in the quartz. In comparison, the bottom cathodoluminescence image of the same area shows growth bands and later fractures within the quartz.

Cathodoluminescence image of a zircon crystal showing a laser ablation pit

Cathodoluminescence images are used to find suitable places on crystals of the mineral zircon to obtain samples for radiometric dating

Tiny samples are burnt out by a laser. The vapourised material is then fed into a mass spectrometer where uranium and lead isotopes are measured to provide a radiometric date for the age of the crystal.

In this example, the cathodoluminescence image shows that the laser ablation pit cuts across two different growth zones on the crystal. As these may have different ages of growth, the date determined for this sample may not be easy to interpret.