mineral

Quartz geode with drusy quartz crystals

Quartz, silicon dioxide (SiO₂), commonly colorless to milky crystalline quartz

AI-generated identification · may be incorrect

Typically hardness 7 Mohs, vitreous luster, white or translucent color, hexagonal crystal structure, and no cleavage (conchoidal fracture). The specimen shows a hollow cavity lined with fine sparkling crystals, possibly with iron-oxide staining or minor associated minerals.

Identified August 22, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater deposits quartz inside cavities or vesicles in volcanic rock, sedimentary concretions, or hydrothermal veins. Individual crystals may form over long periods from late Paleozoic to recent geological ages, depending on locality.

Uses & applications

Used as a mineral specimen, lapidary material, and source of silica; attractive geodes are sold for display and collecting. It is generally not jewelry-grade unless crystals are clear and well formed.

Geological facts

The glittering coating is called drusy or druzy quartz. Quartz is one of Earth’s most abundant minerals and is piezoelectric, producing an electrical charge under pressure.

Field identification & locations

Identify by glassy sparkle, hardness sufficient to scratch ordinary glass, six-sided crystal faces, and lack of cleavage; acid does not react. Common sources include Brazil, Uruguay, Mexico, Morocco, and the western United States.