mineral

Amethyst quartz crystal cluster

Quartz, silicon dioxide (SiO₂), purple variety amethyst

AI-generated identification · may be incorrect

Hardness 7 Mohs; vitreous luster, translucent purple-to-gray crystals, commonly hexagonal prisms with pointed terminations. Quartz has no cleavage and conchoidal fracture; purple color is caused mainly by iron impurities and irradiation.

Identified August 9, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids or volcanic gas cavities deposit quartz crystals, often in basalt geodes; commonly associated with iron staining. Individual deposits range from ancient to geologically recent, depending on host rock.

Uses & applications

Used for ornamental specimens, jewelry, carvings, and metaphysical collecting; crystal clusters are popular display pieces. Value depends on color saturation, transparency, crystal form, size, and locality.

Geological facts

Amethyst is quartz colored by trace iron; heating can turn it yellow-orange, producing citrine. Dark, evenly colored crystals with sharp terminations are generally most desirable.

Field identification & locations

Identify by its purple color, glassy luster, hexagonal crystal habit, hardness, and inability to scratch with a steel knife easily. Common sources include Brazil, Uruguay, Zambia, and Mexico; this specimen may also contain smoky quartz or iron-stained matrix.