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Rhyolite by definition doesn’t have coarse grains. A rock with the composition of rhyolite that is completely coarse grained is going to be a granite or microgranite of some sort. If what you are referring to are phenocrysts in the rhyolite (i.e. a rhyolite with porphyritic texture) or even crystals in a rhyolite tuff, then that is an indication that those ...


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(This homework question is probably long overdue, but here is an answer for the sake of site statistics and future readers.) Magmatic rocks are further classified into extrusive rocks (emplaced at the surface) and plutonic rocks (emplaced in the crust). A magma of the same (silicic) composition can yield a granite if emplaced as a pluton, or a rhyolite if ...


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Topography probably the most distinctive characteristic defining a physiographic province. Each physiographic province has a topographic character that is generally defined. This does not mean the topography is all the same; there can be variation. For instance, the Colorado Plateau has higher-elevation mesas with intermediate to lower elevation valleys. ...


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Just to add to the other answers, If it's mostly water vapor in the gas, then when it cools, the pumice holes would contain liquid water, albeit small amounts compared to the size of the vesicles. This is actually a very important point. When the magma erupted, the vesicle contained very low density H2O gas. Assuming the vesicle remains closed somehow and ...


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