igneous
Iron-stained quartz-rich rock, possibly weathered granite or quartzite
Uncertain from image; likely quartz (SiO₂) with feldspar and iron-oxide staining
AI-generated identification · may be incorrectCoarse, irregular specimen with translucent gray-white quartz, tan/brown feldspar or matrix, and rusty iron-oxide staining. Quartz has Mohs hardness 7, vitreous luster, no cleavage, and conchoidal fracture; exact texture is unclear at this scale.
Identified More igneous →
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Physical properties
Coarse, irregular specimen with translucent gray-white quartz, tan/brown feldspar or matrix, and rusty iron-oxide staining. Quartz has Mohs hardness 7, vitreous luster, no cleavage, and conchoidal fracture; exact texture is unclear at this scale.
Formation & geological history
Likely formed in a silica-rich igneous or metamorphic environment, then altered by oxidation and weathering near the surface. Its geological age cannot be determined visually and depends on locality.
Uses & applications
Common varieties are used as aggregate, building stone, and decorative material; attractive pieces may be kept as cabinet specimens. It is not identifiable as a jewelry-grade gemstone from the photograph.
Geological facts
The brown coloration is probably limonite/goethite coating or staining rather than the primary rock color. A fresh broken surface, streak, and hardness test would substantially improve identification.
Field identification & locations
Common in quartz-bearing veins, granitic terrains, and weathered outcrops worldwide; test whether clear grains scratch glass and inspect for feldspar cleavage and interlocking crystals. Typical collector value is about $5–$25, or up to $50 for an unusually aesthetic locality specimen.
