The practical aims to help develop the critical skill of combining observational data with chemical data and phase diagrams. The practical could be used in conjunction with lectures on layered igneous complexes, magmatic sulphides, and/or electron microscopy-based chemical imaging.

The practical introduces some of the useful educational features of the UK Virtual Microscope. The Virtual Microscope permits the layering of plane-polarised, cross-polarised and reflected light image files, and thereby provides access to students enrolled in courses that do not have reflected light microscopes. This practical has an extra layer of information in the form of elemental maps generated with a scanning electron microscope. In these false-colour maps the colour brightness represents elemental abundance.

Brighter areas in this image represent higher abundances of iron.

The practical is aimed at students with some familiarity with microscopy and should provide sufficient scope to fill a half-day practical time slot.

Pyroxenite sample

The rock selected for the practical is a feldspathic pyroxenite from the Merensky Reef, a chromitite-sulphide mineralised portion of the ca. 2 Ga old Bushveld Complex, South Africa.

The sample was collected by Balz Kamber in 2017 in the Eastern Limb of the Bushveld Complex, from the Der Brochen project area held by Anglo American Platinum Corporation. The thin section was prepared at the Department of Geology, Trinity College Dublin. Optical microscopy scans and EDS maps were made by Alexandra Stavropoulou (ESR1) at the Trinity Center for Microscopy (CMA), with the help of Paul Guyett. Composite maps were assembled by Andy Tindle (