mineral

Blue-gray chalcedony or quartz-rich rock

Microcrystalline quartz, SiO₂; possibly silicified host rock

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; blue-gray to smoky gray, vitreous to waxy luster, translucent edges, and irregular conchoidal fracture. The rusty coating is likely iron-oxide staining; crystal structure is trigonal quartz, although crystals are microscopic.

Identified September 19, 2026More mineral →

Explore Blue-gray chalcedony or quartz-rich rock in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Likely formed when silica-rich fluids filled fractures or replaced volcanic/sedimentary rock, with later oxidation producing the brown-gold surface. Exact age and locality cannot be determined from the photograph.

Uses & applications

Used as lapidary material, cabochons, carvings, and ornamental stone; attractive translucent pieces may be polished. Ordinary rough specimens have little industrial value compared with bulk quartz.

Geological facts

The appearance could overlap with blue-gray chert, agate, silicified volcanic rock, or less commonly blue quartz; a photograph alone cannot distinguish these reliably.

Field identification & locations

Test hardness against glass or a steel file, inspect for waxy luster and conchoidal fracture, and use a streak test (quartz leaves a white streak). Common analogous material occurs in volcanic and sedimentary terrains worldwide.