mineral

Quartz geode (likely amethyst-bearing geode)

Microcrystalline quartz and drusy quartz; SiO₂, with possible iron-stained or amethyst quartz

AI-generated identification · may be incorrect

White to translucent, glassy-to-sparkly drusy crystals lining a hollow cavity; quartz hardness 7 Mohs, no cleavage, conchoidal fracture, trigonal crystal system, and specific gravity about 2.65. The pink-orange specimen behind it may be rose quartz or dyed quartz, but is not the primary specimen.

Identified August 10, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater deposits quartz crystals inside gas vesicles or cavities in volcanic rocks, commonly basalt; geodes are typically Cenozoic to Paleozoic depending on locality. Crystal growth can occur long after the host lava solidifies.

Uses & applications

Used as a decorative specimen, lapidary material, and collector display piece; high-quality amethyst geodes are used in jewelry and interior décor.

Geological facts

The sparkling surface is drusy quartz—many tiny crystals rather than a single crystal. Color zoning reflects trace iron and irradiation; the cavity formed before mineral deposition.

Field identification & locations

Identify by a hollow, rounded host lined with radiating or sugary quartz crystals, hardness that scratches glass, and lack of cleavage. Common sources include Brazil, Uruguay, Mexico, and the United States.