Decomposed granite Decomposed granite Decomposed granite is classification of rock that is derived from granite via its weathering to the point that the parent material readily fractures into smaller pieces of weaker rock. Further weathering yields material that easily crumbles into a mixtures of gravel-sized particles known as grus, that in turn may break down to produce a mixture of clay and silica sand or silt particles. Different specific granite types have differing propensities to weather, and so differing likelihoods of producing decomposed granite. It has practical uses that include its incorporation into paving and driveway materials, residential gardening materials in arid
Quartz arenite Quartz arenite A quartz arenite or quartzarenite is a sandstone composed of greater than 90% detrital quartz, with limited amounts of other framework grains (feldspar, lithic fragments, etc.) and matrix. It can have higher-than-average amounts of resistant grains, like chert and minerals in the ZTR index. The term 'quartz arenite' is derived from the main component (quartz) and arenite, a Latin term for a rock with sand-sized grains. In some literature, these can be called orthoquartzites, a confusing term which usually refers to the metamorphic rock quartzite, though most metamorphic quartzites are diagentically fused from quartz arenites. The term "quartzose