Virtual Atlas of Opaque and Ore Minerals
Cassiterite, wolframite and zircon. Glen Gairn, Scotland
Euhedral cassiterite (medium grey, bottom right) with small inclusions of wolframite (higher reflectance, centre of cassiterite) is replaced by phyllosilicates (white mica) (bottom centre) and quartz. Euhedral tabular wolframite (light grey, highest reflectance, centre top) is zoned with poorly polished outer rims which have altered to fine-grained scheelite (centre left). Euhedral zircon (grey with very faint internal reflections, centre left) has two wolframite crystals growing from it. The low reflectance core of the larger wolframite (centre left) is scheelite. White mica (tabular, poorly polished) is intergrown with quartz and unaltered feldspar; the latter two cannot be distinguished in this section. Opaque phases below the surface of the section are responsible for the 'shadows' within the silicates.
Polished thin section, plane polarized light, x 160, air