Quartz

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

Formed in a wide variety of geological environments including igneous, metamorphic, and sedimentary rocks. Commonly crystallizes from silica-rich hydrothermal solutions or cooling magma.

Used in electronics (oscillators), glass manufacturing, abrasives, gemstones, and ornamental objects.

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

Identified by its high hardness (scratches glass easily), lack of cleavage, and conchoidal fracture. Found worldwide in nearly all rock types.