Thin section of Carboniferous basalt, Corrie (Hunterian Museum, rock number AH5029)

This is from the shore just north-east of Clach an Fhionn, the large white granite boulder on the north outskirts of the village. The rock is very rich in large phenocrysts of magnesium-rich olivine (on the right - colourless, with curving cracks), and clinopyroxene (on the left, with a faint greyish or brownish tint, plus faint cleavages). Between these, the groundmass consists of clinopyroxene, plagioclase feldspar, and magnetite. Between crossed polars, the olivine and clinopyroxene phenocrysts show bright birefringence colours, and the plagioclase crystals show their typical lamellar (striped) twinning. (NB the image above was taken with crossed polars).

Courtesy of Dr John Faithful - Hunterian Museum