metamorphic

Quartz-rich gneiss or quartzite

Quartz–feldspar–mica metamorphic rock; exact identification requires a fresh surface and tests

AI-generated identification · may be incorrect

Hardness about 6.5–7; pale gray to cream with rusty-brown iron staining, granular texture, and vitreous to dull luster. The specimen appears massive and weakly foliated, with abundant interlocking quartz and possible feldspar; cleavage is poor or absent and specific gravity is roughly 2.6–2.7.

Identified September 6, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely formed when quartz-rich sediment or granitic rock was metamorphosed under elevated temperature and pressure, probably during a Precambrian or Paleozoic mountain-building event. Weathering produced the iron-oxide staining.

Uses & applications

Used locally as durable aggregate, paving stone, or decorative stone; attractive pieces may be collected, but this specimen is not gem quality.

Geological facts

Quartzite is notably resistant to scratching and weathering, whereas gneiss commonly shows compositional banding. A steel file should not easily scratch the quartz-rich grains; acid should produce no reaction.

Field identification & locations

Common in metamorphic terrains and glacial or stream deposits worldwide. Distinguish quartzite from granite by its fused, sugary quartz texture and from gneiss by checking for banding and visible feldspar/mica layers.