metamorphic
Quartzite with Mica / Gneiss Pebble
Metamorphic Rock (Quartz-Feldspar-Mica aggregate)
Hardness: 6-7 on Mohs scale; Color: Mottled white, grey, and dark charcoal/black; Luster: Vitreous to dull/sub-metallic in micaceous regions; Grain: Medium-grained, slightly foliated texture; Cleavage: Poor/indistinct in quartz areas, basal cleavage in mica flakes.
- Hardness
- 6-7 on Mohs scale
- Color
- Mottled white, grey, and dark charcoal/black
- Luster
- Vitreous to dull/sub-metallic in micaceous regions
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Mottled white, grey, and dark charcoal/black; Luster: Vitreous to dull/sub-metallic in micaceous regions; Grain: Medium-grained, slightly foliated texture; Cleavage: Poor/indistinct in quartz areas, basal cleavage in mica flakes.
Formation & geological history
Formed via regional metamorphism of igneous (like granite) or sedimentary (like sandstone) parent rocks under high temperature and pressure, recrystallizing quartz, feldspar, and mica.
Uses & applications
Commonly used in crushed stone aggregate, road base, river pebble landscaping, and educational geology collections.
Geological facts
Small pebbles found along riverbeds, beaches, or gravel areas often represent eroded fragments of larger metamorphic metamorphic belts, transported over long distances by water.
Field identification & locations
Look for alternating bands or mottled patches of hard white quartz and darker minerals (biotite/amphibole). Easily found in riverbeds, glacial tills, and gravel deposits worldwide.
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