metamorphic
River-worn Quartzite / Soapstone
Metamorphic Rock (Quartzite/Talc-schist)
Hardness: 1-7 depending on exact composition (6-7 for quartzite, 1-2 for soapstone/talc); Color: Pale greyish-green to off-white; Luster: Dull to waxy/greasy; Texture: Fine-grained, stream-rounded pebble; Cleavage: Poor or absent in massive varieties.
- Color
- Pale greyish-green to off-white
- Luster
- Dull to waxy/greasy
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Physical properties
Hardness: 1-7 depending on exact composition (6-7 for quartzite, 1-2 for soapstone/talc); Color: Pale greyish-green to off-white; Luster: Dull to waxy/greasy; Texture: Fine-grained, stream-rounded pebble; Cleavage: Poor or absent in massive varieties.
Formation & geological history
Formed under elevated temperatures and pressure through regional or contact metamorphism of quartz-rich sandstone or ultramafic igneous rocks, subsequently eroded and rounded by river or stream action.
Uses & applications
Commonly used for landscaping, decorative pebbles, carving (if soft soapstone variety), construction aggregate, or lapidary tumbling.
Geological facts
Stream-rounded river rocks acquire their smooth, bulbous shape over thousands of years as water currents roll them along riverbeds, wearing away sharp edges.
Field identification & locations
Identified in the field by its smooth, water-worn outer surface and light grey-green color. A simple scratch test with a steel key or pocket knife will determine if it is hard quartzite (won't scratch) or soft soapstone/steatite (scratches easily).
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