Quartz

Hardness of 7 on the Mohs scale; color varies widely including clear, white, gray, purple; vitreous luster; hexagonal crystal system; specific gravity of 2.65.

Formed in a wide variety of geological environments, commonly in igneous, metamorphic, and sedimentary rocks. Often crystallizes from silica-rich hydrothermal veins and pegmatites.

Used in electronics, oscillators, glassware, abrasives, gemstones, and construction materials.

Quartz is one of the most abundant minerals in the Earth's continental crust and exhibits strong piezoelectric properties, meaning it can generate an electric charge under mechanical stress.

Identified by its high hardness (scratches glass), lack of cleavage, and typical crystal habit or conchoidal fracture. Found globally.