What is Quartz?
Quartz is the second most abundant mineral in the Earth’s crust after feldspar. It occurs in nearly all acid igneous, metamorphic, and sedimentary rocks. It is an essential mineral in such silica-rich felsic rocks as granites and rhyolites. It is highly resistant to weathering and tends to concentrate in sandstones and other detrital rocks. Microcrystalline varieties of silica known as agate and jasper consist of a fine network of quartz. Metamorphism of quartz-bearing igneous and sedimentary rocks typically increases the amount of quartz and its grain size. Quartz is piezoelectric which means it develops positive and negative charges on alternate prism edges when it is subjected to pressure or tension. The charges are proportional to the change in pressure. Because of its piezoelectric property, a quartz plate can be used as a pressure gauge, as in depth-sounding apparatus. Just as compression and tension produce opposite charges, the converse effect is that alternating opposite charg
