igneous
Weathered quartz-rich pebble
Likely granitic or felsic igneous rock; quartz (SiO₂) with feldspar and minor mafic minerals
AI-generated identification · may be incorrectHardness about 6–7; rounded, rough granular texture with pale gray-green, cream, and rusty weathering colors; dull to weakly vitreous luster. Interlocking crystalline structure; cleavage is mainly from feldspar, not the whole pebble.
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Physical properties
Hardness about 6–7; rounded, rough granular texture with pale gray-green, cream, and rusty weathering colors; dull to weakly vitreous luster. Interlocking crystalline structure; cleavage is mainly from feldspar, not the whole pebble.
Formation & geological history
Originally crystallized slowly from silica-rich magma, likely millions to billions of years ago, then eroded and rounded by water or glacial transport. Rust-colored areas indicate oxidation of iron-bearing minerals.
Uses & applications
Usually valued as a natural landscaping or teaching specimen; uncommonly used as aggregate or decorative stone. This individual pebble has little jewelry or commercial value.
Geological facts
Its rounded shape reflects transport rather than its original igneous form. The dark background appears to be asphalt, but the centered object is a natural geological pebble.
Field identification & locations
Identify by visible interlocking grains, abundant light quartz/feldspar, and hardness sufficient to scratch glass; a streak, acid, and close-grain examination would refine identification. Common in stream gravels, glacial deposits, and crushed-stone environments.
