igneous
Iron-stained quartz-rich rock, possibly weathered granite or quartzite
Indeterminate quartz–feldspar aggregate with iron-oxide staining; likely granitic or hydrothermal material
AI-generated identification · may be incorrectTan, cream, pink, and rusty-brown granular specimen with a dull to locally glassy luster; visible quartz-like grains and probable feldspar. Estimated Mohs hardness 6–7, no obvious cleavage at specimen scale, and moderate density around 2.6–2.7 g/cm³.
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Physical properties
Tan, cream, pink, and rusty-brown granular specimen with a dull to locally glassy luster; visible quartz-like grains and probable feldspar. Estimated Mohs hardness 6–7, no obvious cleavage at specimen scale, and moderate density around 2.6–2.7 g/cm³.
Formation & geological history
Likely formed from quartz and feldspar crystallization in an igneous rock or silica-rich hydrothermal vein, later fractured and weathered; iron oxides produced the red-brown staining. Exact age and origin cannot be determined from the photograph.
Uses & applications
Usually a common field specimen with little commercial value; fresh material may be used as aggregate or decorative stone, while attractive quartz-bearing pieces can be collected.
Geological facts
The rusty coloration is commonly caused by hematite or limonite coatings rather than abundant metallic iron. A glassy scratch on unglazed ceramic and resistance to a steel knife would support substantial quartz content.
Field identification & locations
Common in weathered granitic terrains, quartz veins, and mineralized zones worldwide; inspect a freshly broken surface and test for visible quartz, feldspar cleavage, and iron-oxide coatings. Approximate value: $1–$10 for an ordinary hand specimen; more only if crystals or unusual mineralization are present.
