mineral

Raw yellow chalcedony or quartz-bearing rock

Microcrystalline silica, SiO₂ (likely chalcedony/quartz; exact identification requires testing)

AI-generated identification · may be incorrect

Pale yellow, translucent-to-opaque, with a waxy to dull luster and irregular fracture; quartz-family hardness is about 7 Mohs, with no cleavage. The rough granular surface may reflect druzy quartz or weathering, while the color could result from iron staining or inclusions.

Identified September 16, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed when silica-rich groundwater filled cavities or fractures in volcanic or sedimentary rock, followed by crystallization and oxidation; age depends on its source locality. It commonly occurs in geodes, nodules, and hydrothermal veins.

Uses & applications

Used as a lapidary material, ornamental stone, cabochon, or collector specimen; ordinary pieces have little industrial value compared with high-purity quartz.

Geological facts

A steel knife should not scratch genuine quartz-family material, though a streak test is generally unhelpful because quartz is harder than the streak plate. Acid does not normally react with chalcedony or quartz.

Field identification & locations

Common worldwide, including Brazil, Uruguay, Mexico, Turkey, and the western United States. Confirm with hardness, translucency, specific gravity (about 2.6), and ideally magnification or laboratory testing; the photograph alone cannot distinguish chalcedony from yellow quartz or another silica-rich mineral.