metamorphic
Quartzite with Feldspar and Mica (Granitic Gneiss Pebble)
Metamorphic Rock / Quartzite / Granitic Gneiss
Hardness: 6-7 on Mohs scale. Color: Tan, salmon-pink, off-white, and dark greyish-green streaks. Luster: Vitreous to dull. Texture: Fine to medium-grained, water-worn rounded pebble. Specific Gravity: ~2.6-2.7.
- Hardness
- 6-7 on Mohs scale
- Color
- Tan, salmon-pink, off-white, and dark greyish-green streaks
- Luster
- Vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Tan, salmon-pink, off-white, and dark greyish-green streaks. Luster: Vitreous to dull. Texture: Fine to medium-grained, water-worn rounded pebble. Specific Gravity: ~2.6-2.7.
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone or igneous granitic rocks under intense heat and pressure deep within Earth's crust. Subsequently eroded, weathered, and rounded by water transport in rivers or ocean shores.
Uses & applications
Used in construction as crushed stone, gravel, and landscape decorative rock. River pebbles of this type are also popular for rock tumbling and craft painting.
Geological facts
Water-worn pebbles like this often travel miles down rivers or along coastlines over thousands of years, wearing away soft minerals and leaving behind the hardest quartz and feldspar matrix.
Field identification & locations
Field Identification: Look for a smooth, rounded surface with visible alternating bands or patches of pink/tan feldspar, clear-to-white quartz, and dark micaceous or amphibole veins. Hard enough to scratch glass. Widely found in gravel beds, river channels, and glacial till deposits.
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