Quartz

Hardness of 7 on the Mohs scale, white or milky color, vitreous to greasy luster, trigonal crystal system, conchoidal fracture, specific gravity of 2.65.

Formed in a wide variety of geological environments, including igneous, metamorphic, and sedimentary rocks, often crystallized from hydrothermal solutions or silicate melts over millions of years.

Used in glassmaking, electronics, oscillators, gemstones, and abrasive materials.

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

Easily identified by its high hardness (scratches glass) and conchoidal fracture; found worldwide in river gravels, beaches, and vein deposits.