Transactions . solated quartz grains are comparatively free of inclusions andshow slight effects of strain. Some of the quartz, like thesericite and carbonates, is probably secondary; but theselarger ragged grains at least, are probably the remnants of pheno-cr>sts in the original igneous rock. The quartz has characterswhich are more common in volcanic than in plutonic rocks. Thereare aLso some patches of brownish white opaque substance, similarto that which results from decomposition of titanite. Pyrite isa characteristic constituent, often occurring in well formed crystals.
Transactions . solated quartz grains are comparatively free of inclusions andshow slight effects of strain. Some of the quartz, like thesericite and carbonates, is probably secondary; but theselarger ragged grains at least, are probably the remnants of pheno-cr>sts in the original igneous rock. The quartz has characterswhich are more common in volcanic than in plutonic rocks. Thereare aLso some patches of brownish white opaque substance, similarto that which results from decomposition of titanite. Pyrite isa characteristic constituent, often occurring in well formed crystals. Another specimen has its quartz chiefly in the form of veryminute particles. Among these quartz grains are numerous flakesof sericite arranged with their longer dimensions parallel andgiving the rock its schistose character. Irregularly distributedthrough the fine grained quartz and sericite, arc much larger par-ticles of a carbonate. Pyrite and small particles of a light colouredopaque .substance are
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Keywords: ., book, bookcentury1800, booksubjectmineralindustries, bookyear1895
