Browse Items (2 total)

Hand Specimen Pink-brown, porphyritic rock with a very fine-grained groundmass. Abundant pink macrocrysts (5-10 mm). Phenocrysts of feldspar (2-4 mm) and quartz (2-4 mm). Accessory black mineral. Thin-section Quartz - Rounded phenocrysts (1-4…

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…