igneous
Iron-stained quartz-rich rock, likely pegmatite or quartz vein fragment
Quartz (SiO₂) with feldspar, mica, and iron-oxide/hydroxide staining; possibly weathered granite pegmatite
AI-generated identification · may be incorrectHardness about 6–7 Mohs; cream, gray, yellow, and reddish-brown colors; vitreous to dull luster; interlocking granular crystals with no obvious cleavage in quartz, while feldspar shows cleavage. Specific gravity is roughly 2.6–2.7.
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Physical properties
Hardness about 6–7 Mohs; cream, gray, yellow, and reddish-brown colors; vitreous to dull luster; interlocking granular crystals with no obvious cleavage in quartz, while feldspar shows cleavage. Specific gravity is roughly 2.6–2.7.
Formation & geological history
Likely formed from silica-rich magma or hydrothermal fluids that crystallized quartz and feldspar, later altered and stained by oxidized iron near the surface. Exact geological age and locality cannot be determined from the photograph.
Uses & applications
Common material is mainly a collector specimen or lapidary rough; attractive pieces may be polished. Quartz-rich pegmatite also supplies quartz and feldspar for glass, ceramics, and industrial materials.
Geological facts
The yellow-brown coloration commonly comes from limonite/goethite coatings rather than naturally yellow quartz. Dark reflective patches may represent mica, iron oxides, or another accessory mineral.
Field identification & locations
Look for glassy quartz, blocky or creamy feldspar, granular texture, and reddish-brown iron staining; it should scratch ordinary glass but not a steel knife. Common in granitic terrains, pegmatite districts, and quartz-vein outcrops.
