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
Fall River granite of the underlying granite is the Hixville Fault near Dartmouth, Massachusetts. From a distance, the rock exhibits a distinctive tan-gray color. Viewed up close, it is more pink. The granite is very hard and durable, but cannot be polished very well. As a result, its appearance on a building is almost always somewhat rough, rather than the sharp lines of other types of building stone. Edmund Hitchcock, of the 1841 Geological Survey of Massachusetts gave the following description of the granite: But no rock can be finer for architectural purposes than the granite of Troy...The feldspar of this rock is