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, 19:24, 23 January 2019
Plot of modern beach sands and their source terranes shows how the amount of nonundulatory, undulatory, and polycrystalline quartz grains and the number of crystals in polycrystalline grains can help determine quartz provenance (from [[Quartz|Basu et al., 1975]]). From From AAPG Memoir 109—A Color Guide to the Petrography of Sandstones, Siltstones, Shales, and Associated Rocks, [http://store.aapg.org/detail.aspx?id=1250 Chapter 1].