I like in the sacramento country area in california and i was wondering if there was a website with locations where one might find quartz crystals?
Gneiss is a medium to high grade metamorphic rock and so any other metamorphic rock of lower grade can be metamorphosed into a schist. For a schist you could have a mudstone, shale, phyllite, slate or felsic to igneous rock protolith... there are so many possibilities but for a high silica schist your best bet would be a felsic igneous rock such as granite or rhyolite.
A conglomerate of quartz pebbles and quartz cement might metamorphose into a schist consisting almost entirely of differently colored and/or pure quartz blebs. But this is a speculation based on specimens which are on one side conglomerates of quartz-in-quartz, and, on the other, interleaved, flattened blebs of differently colored quartz--as a quartz schist.
It would not be a Quartz Schist (no such thing) it would be a protolithic siliceous shale that becomes a quartz rich Schist. Granite will develop a gnissic texture as would any sandstone other than an Orthoquartzite which would become a Quartzite.
perhaps you would prefer to call it a quartz-mica schist? it would only have the quartz part if there is, in fact, quartz, in the rock. siliceous implies the probability of free quartz but doesn't impose it. To have a micaceous schist requires aluminosilicates in the protolith (feldspars or clays would be the most common sources). there are a lot of protoliths that could convert into a quartz-mica schist on metamorphism. a dirty sandstone, an arkose sandstone or wacke, maybe could convert into a quartz-mica schist. Interbeded sand-silt-shale or pelitic source also could go quartz-mica schist. Intermediate to felsic lavas (generally extrusives because of crystallinity and stability issues) could also go qz-mica schist. the real world is a lot more complex than the simple models we are taught in the early level courses.
