Quartz

Hardness of 7 on the Mohs scale, vitreous luster, transparent to translucent, hexagonal crystal system, conchoidal fracture, specific gravity of 2.65.

Forms in a wide variety of geological environments including igneous, metamorphic, and sedimentary rocks, often crystallizing from hydrothermal solutions or silica-rich magmas.

Used in electronics, watches, glassmaking, abrasives, and as a popular gemstone or specimen for collectors.

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

Easily identified by its hardness (scratches glass), conchoidal fracture, and lack of cleavage. Found worldwide in almost every geological setting.