Quartz is the second most abundant mineral in 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, Quartz is very hard and shiny, and it’s also quite common. There are many different types of quartz, and the rarest ones are considered semi-precious gemstones, like citrine and amethyst. This is the quartz that’s used to make jewellery. Its chemical name is silicon dioxide, and it has a crystal structure. Quartz comes from the German Quartz, “rock crystal