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ADAMELLITE (QUARTZ MONZONITE), IG-5. California. Medium to coarse grain, light pink, minor biotite in 1-3 mm grains. ALASKITE, see under GRANITE. ANDESITE PORPHYRY, IG-10. California. Phenocrysts of white plagioclase crystals, 5mm to 1 cm, in compact gray or red groundmass. Check. AMYGDALOIDAL ANDESITE, IG-10C. Amygdules, usually lined with analcite crystals in brown andesite matrix. Check for p&a. HORNBLENDE ANDESITE, IG-10D. Nevada. Porphyritic. Scattered black vitreous hornblende phenocrysts to 1 cm in light to dark gray or hematite rich red-gray groundmass. AUGITE ANDESITE, IG-10H. Nevada. Porphyritic with 0.2-2 mm phenocrysts of andesine and augite in light reddish gray partially devitrified glass. Cp20 - ANORTHOSITE, IG-15. Cost J. California. Light gray to light lavender-gray andesine feldspar with occasional minor hypersthene or chlorite. |