Rock Identifier
Quartz geode/drusy quartz cluster (Quartz (SiO₂), with probable feldspar host and minor iron-oxide staining) — mineral
mineral

Quartz geode/drusy quartz cluster

Quartz (SiO₂), with probable feldspar host and minor iron-oxide staining

AI-generated identification · may be incorrect

Colorless to white drusy quartz crystals with vitreous luster; quartz hardness 7, trigonal crystal system, no cleavage, conchoidal fracture, specific gravity about 2.65. The rounded pink-gray matrix may be altered feldspar or rhyolitic volcanic rock.

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Physical properties

Colorless to white drusy quartz crystals with vitreous luster; quartz hardness 7, trigonal crystal system, no cleavage, conchoidal fracture, specific gravity about 2.65. The rounded pink-gray matrix may be altered feldspar or rhyolitic volcanic rock.

Formation & geological history

Likely formed when silica-rich groundwater deposited quartz crystals in cavities or fractures of volcanic rock, commonly during cooling or later hydrothermal activity. Exact geological age and locality cannot be determined from the photograph.

Uses & applications

Used as a decorative mineral specimen, lapidary material, and occasionally in jewelry; quartz is also important in glass, electronics, and industrial abrasives.

Geological facts

“Drusy” describes a coating of many tiny crystals rather than a single large crystal. The sparkling surface is produced by crystal faces reflecting light.

Field identification & locations

Identify by the fine, glittering quartz coating, hardness, and absence of cleavage; quartz will scratch glass, though testing may damage the specimen. Common sources include Brazil, Uruguay, Mexico, Morocco, and the western United States.