GEO 2163 Lecture Notes - Lecture 10: Quartzite, Chert, Chalcedony
21 Sep 2017
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Document Summary
Jasper is a microcrystalline form of the mineral quartz, and does not occur in visible crystals. It most often is in massive form, but may also be botryoidal, mammilaryand stalactitic formations. , as smooth rounded pebbles, and as nodules cavity-fillings such as in fractures and geodes, nodular, reniform or as a replacement of other minerals and wood. Trigonal typically anhedral, euhedral crystals only in felsic volcanic rocks and in cavity fillings or veins none. Colorless, white, gray white the most abundant single mineral in the earth"s crust, particularly in granitic rocks and their volcanic and metamorphic equivalents; also sandstone, quartzite, chert, jasper, banded iron formation, hydrothermal veins;v. Most often as protruding clusters of pyramids on a matrix base. Also occurs as tall prismatic crystals, as short stubby crystals, in drusy aggregates, massive, in geodes, and as rounded waterworn stones none. Sometimes banded with purple and whitish lines. white. Occurs in all mineral environments, especially in igneous environme n.
