7.1 Hornblende-biotite quartz diorite (tonalite). Alpine, San Diego Co., CA. White, irregular to rectangular plagioclase with gray glassy quartz surround yellow-green epidote, greenish-black rectangular hornblende, and small to large poikilitic brownish-black biotite grains in this rock. Note the large amoeba-like biotite in the upper center containing enclosed grains of quartz and plagioclase. Another poikilitic biotite present at the upper center far left shows reflections from cleavage. In the upper right and elsewhere, rectangular plagioclase grains, including a zoned grain at the right center, show bright reflections from cleavage.