mineral

Quartz and amethyst specimens

Quartz (SiO₂), including purple amethyst variety

AI-generated identification · may be incorrect

The foreground specimens appear to be rough quartz: a milky-white piece and a small purple amethyst crystal. Mohs hardness 7, vitreous luster, hexagonal crystal system, poor cleavage, conchoidal fracture, and specific gravity about 2.65; purple color comes from iron impurities and irradiation.

Identified August 17, 2026More mineral →

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Physical properties

Formation & geological history

Quartz crystallizes from silica-rich hydrothermal fluids, cavities in volcanic rocks, and pegmatites; amethyst commonly forms in gas bubbles of basaltic lava. Specimens may range from ancient to geologically recent depending on the host rock.

Uses & applications

Used for collecting, ornamentation, countertops, abrasives, glass, and electronics; transparent amethyst is used in jewelry. These small rough pieces generally have modest commercial value.

Geological facts

Amethyst is the traditional purple variety of quartz and ranks 7 on the Mohs scale, making it durable but still susceptible to scratching by harder materials such as topaz or corundum.

Field identification & locations

Identify quartz by its glassy luster, lack of prominent cleavage, conchoidal fracture, and hardness; amethyst is distinguished by purple coloration. Common sources include Brazil, Uruguay, Mexico, Zambia, and the United States.