mineral

Botryoidal chalcedony with iron-oxide staining

Microcrystalline quartz (SiO₂), likely iron-oxide-bearing chalcedony

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; gray to honey-brown with orange-brown iron staining, waxy to slightly vitreous luster, and rounded botryoidal (“grape-like”) surfaces. It has cryptocrystalline quartz structure, no visible cleavage, and conchoidal fracture; specific gravity is about 2.6.

Identified August 15, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed when silica-rich groundwater deposited chalcedony in cavities, fractures, or volcanic-rock vesicles, with later oxidation of iron producing the orange-brown colors. The exact geological age cannot be determined from the photograph.

Uses & applications

Used as a lapidary and display material; attractive pieces may be cut, polished, or made into cabochons. Ordinary specimens have little industrial or jewelry value.

Geological facts

Botryoidal chalcedony commonly develops from repeated silica coatings around a cavity or nucleus. The gray areas may reflect included minerals or contrasting silica growth, while the orange coloration is probably goethite or hematite.

Field identification & locations

Look for a waxy surface, translucent edges, rounded silica bumps, conchoidal fracture, and hardness sufficient to scratch glass; a steel file should not easily scratch it. Common sources include volcanic terrains and silica-rich hydrothermal veins worldwide.