mineral

Quartz geode clusters

Microcrystalline quartz (SiO₂), with possible chalcedony and minor iron-oxide staining

AI-generated identification · may be incorrect

Hardness 7 Mohs; white to colorless, vitreous to sparkling drusy luster, commonly botryoidal or crystalline coatings lining cavities. Quartz is trigonal and lacks cleavage, with conchoidal fracture; the pieces appear cut or broken open and may be lightly dyed or coated.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed when silica-rich groundwater filled vesicles or cavities in volcanic rock, depositing chalcedony and later quartz crystals over long periods; commonly Cenozoic to older, depending on source locality.

Uses & applications

Used as decorative specimens, crystal displays, lapidary material, and occasional jewelry components; less suitable for structural construction because these are small geodes.

Geological facts

The glittering surface is drusy quartz—many tiny crystal tips that reflect light. The outer rind is typically chalcedony or weathered volcanic material, while the hollow center records the original cavity.

Field identification & locations

Identify by a hard, glassy sparkle, quartz-like fracture, and crystals lining a hollow cavity; common sources include Brazil, Uruguay, Mexico, Morocco, and the United States. A steel file should not easily scratch quartz.