Granite; Loch
Laxford, NW Scotland
This cut surface of a hand specimen shows the typical
minerals of a granite. There are two varieties of feldspar:
potassium feldspar is pink in colour, sodium feldspar is
white. Quartz is glassy and transparent, appearing grey in
hand specimen. These three minerals make up more than 95% of
the rock Small amounts of black minerals are present: these
are magnetite (iron oxide) and biotite (dark mica). The
texture consists of interlocking crystals up to 1 cm across.
Although in many granites the larger feldspars may show
regular blocky shapes, in this one they are mostly more
rounded.