igneous
Quartz-rich breccia (likely milky quartz with iron staining)
Microcrystalline to coarse quartz, SiO₂, in a brecciated silica-rich matrix; exact identification is uncertain from the photograph
AI-generated identification · may be incorrectWhite to gray, opaque-to-translucent angular quartz fragments with tan-brown iron-oxide staining; vitreous to dull luster, no obvious cleavage, Mohs hardness about 7, and specific gravity near 2.65.
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Physical properties
White to gray, opaque-to-translucent angular quartz fragments with tan-brown iron-oxide staining; vitreous to dull luster, no obvious cleavage, Mohs hardness about 7, and specific gravity near 2.65.
Formation & geological history
Likely formed when silica-rich rock fractured and was cemented by later quartz-bearing fluids, commonly in hydrothermal veins; its age depends on the host formation and cannot be determined visually.
Uses & applications
Used mainly as a collector specimen or lapidary material; quartz-rich rock may be crushed for aggregate or silica, though this small piece has little commercial value.
Geological facts
Quartz commonly shows conchoidal fracture rather than cleavage and can scratch ordinary glass. Brown coloration is typically caused by limonite or hematite coatings and inclusions.
Field identification & locations
Look for glassy quartz fragments, irregular fracture, hardness, and lack of reaction to dilute hydrochloric acid; common in hydrothermal veins and silicified fault zones worldwide.
