| Text Description: |
Near the contact with Finger Bay volcanics, a dark-gray porphyritic feldspathic granodiorite, color index commonly 10 to 15, is a conspicuous and characteristic rock. Analyzed specimen no. 5, from the contact at the north end of Bay of Waterfalls, is one of these. About one-third of the rock is large (+/- 7 mm) crystals of cloudy, dark-gray zoned plagioclase that give it the appearance of anorthosite. A preferred orientation of these crystals was observed in several outcrops. The large plagioclase crystals are set in a fine, subhedral-granular matrix. The mode is: plagioclase, 65.5 percent; alkali feldspar and orthoclase, 13 percent; quartz, 8.2 percent; hornblende, 7.6 percent; clinopyroxene, 1.6 percent; opaque oxide, 3.0 percent; biotite, 0.4 percent; chlorite, 0.3 percent; apatite, 0.3 percent, and sphene, 0.1 percent. |
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