Browse Items (3 total)

Hand Specimen Mostly moderately coarse-grained (typically 1-2 mm), some regions finer-grained (typically ~0.5 mm). “Salt and pepper” appearance being speckled black and white. Two black phases, biotite mica and hornblende amphibole. White…

Hand Specimen Medium to coarse-grained rock with a granular texture. White feldspar laths 2-4 mm long are clearly visible. Other phases: pink feldspar, black biotite mica, black hornblende amphibole and pale grey quartz. These grains are…

Hand Specimen This rock has a porphyritic texture. Phenocrysts of white feldspar up to 30mm long are surrounded by a coarse groundmass of quartz, biotite and white feldspar. Thin-section Alkali feldspar (orthoclase) - Grains typically 2-4mm…