Gruesome California Crime Stories That May Play A Part In âTrue Detectiveâ Season 2. Nic Pizzolatto isnât letting us into his warped, deviant mind when it comes to salient plot points surrounding the second season of the highly-acclaimed HBO anthology series, True Detective, but he has dropped a few hints.
Rhyolite: Fine-Grained Felsic Rock Most rhyolites are light gray to pinkish in color, but red or even black rhyolites are not rare. Most rhyolites are porphyritic and are identified by the quartz phenocrysts and white to salmon K-feldspar phenocrysts. The groundmass is aphanitic or even glassy.
Felsic rocks are commonly oversaturated and contain free quartz (SiO2), intermediate rocks contain little or no quartz or feldspathoids (undersaturated minerals), and mafic rocks may contain abundant feldspathoids. This broad grouping on the basis of mineralogy related to silica content is used in many modern classification schemes.