mineral
Quartz-rich crystal aggregate
Quartz (SiO₂), possibly druzy quartz with iron-oxide staining
AI-generated identification · may be incorrectHardness 7 Mohs; pale cream to honey-yellow, vitreous to sugary luster, and translucent crystal faces. Quartz is trigonal, lacks cleavage, and has specific gravity about 2.65; the yellow color may reflect inclusions or surface staining.
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Physical properties
Hardness 7 Mohs; pale cream to honey-yellow, vitreous to sugary luster, and translucent crystal faces. Quartz is trigonal, lacks cleavage, and has specific gravity about 2.65; the yellow color may reflect inclusions or surface staining.
Formation & geological history
Likely formed when silica-rich hydrothermal fluids filled a cavity or fracture, allowing many small quartz crystals to grow. The specimen’s exact age and locality cannot be determined from the photograph.
Uses & applications
Used mainly as a decorative and collecting specimen; attractive druzy material may be set in jewelry or used in cabochons and ornaments. Common rough pieces generally have modest commercial value.
Geological facts
Quartz commonly forms six-sided prisms terminated by pyramids, although granular aggregates may obscure the crystal shape. It can scratch ordinary glass and does not react with dilute hydrochloric acid.
Field identification & locations
Common in geodes, veins, and altered volcanic or sedimentary rocks worldwide, including Brazil, Mexico, Morocco, and the United States. Confirm with a glass-scratch test and inspection for conchoidal fracture; yellow coloration alone does not prove citrine.
