Decomposed granite of silica sand, silt particles, and clay. Different specific granite types have differing propensities to weather, and so differing likelihoods of producing decomposed granite. The parent granite material is a common type of igneous rock that is granular, with its grains large enough to be distinguished with the unaided eye (i.e., it is phaneritic in texture); it is composed of plagioclase feldspar, orthoclase feldspar, quartz, mica, and possibly other minerals. The chemical transformation of feldspar, one of the primary constituents of granite, into the clay mineral kaolin is one of the important weathering processes. The presence of clay allows water
Granite, Colorado between high, sheer rock outcroppings of buff/pink-colored Precambrian granite. Granite lies at the center of the Colorado Mineral Belt (CMB), a 50 mile-wide strip that runs north and south for 300 miles. Mineralization of the CMB came primarily by way of intrusions of Tertiary Period magmas. The primary ores of the CMB were generally deposited as mixed metal sulfide mineral veins containing pyrite, galena, sphalerite, chalcopyrite, and gold, silver, and copper. During the last glacial period native gold was freed from the host rock and deposited along the ancient roaring Arkansas River bed - much larger than it is today