mineral
Weathered quartz-rich rock, possibly milky quartz or quartzite
Quartz (SiO₂), likely with iron-oxide staining and minor feldspar or carbonate impurities
AI-generated identification · may be incorrectCream to tan, mostly massive and granular, with vitreous to dull luster and irregular fracture; quartz hardness is about 7 Mohs, with no cleavage and specific gravity near 2.65. The porous, rusty-brown surface suggests weathering and iron-oxide coatings.
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Physical properties
Cream to tan, mostly massive and granular, with vitreous to dull luster and irregular fracture; quartz hardness is about 7 Mohs, with no cleavage and specific gravity near 2.65. The porous, rusty-brown surface suggests weathering and iron-oxide coatings.
Formation & geological history
Likely formed as a hydrothermal quartz vein or quartz-rich metamorphic rock, later exposed and weathered; its precise geological age cannot be determined from the photograph. The brown coloration commonly comes from limonite/goethite formed during oxidation.
Uses & applications
Common quartz-rich specimens are used for teaching, collecting, aggregate, and occasionally ornamental stone; this irregular specimen has little commercial jewelry value unless cutting reveals attractive clarity or patterns.
Geological facts
Quartz is one of Earth’s most abundant minerals and is a major component of granite, sandstone, and many veins. Iron staining can produce colors ranging from yellow-brown to red.
Field identification & locations
Identify it by its glassy fracture, hardness—scratching ordinary glass—and lack of cleavage. Common settings include quartz veins, granitic terrains, and metamorphic belts; confirmatory testing would require a scratch test and closer examination for feldspar or carbonate.
