metamorphic
Grey River Stone (Gneiss/Schist mix)
Foliated Metamorphic Rock (variable mineral formula)
Hardness: 6-7 (Mohs); Color: Grey with slight greenish/white speckling; Luster: Dull/Sub-vitreous; Structure: Foliated with fine mineral banding; Specific Gravity: 2.7-3.2
- Hardness
- 6-7 (Mohs)
- Color
- Grey with slight greenish/white speckling
- Luster
- Dull/Sub-vitreous
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Physical properties
Hardness: 6-7 (Mohs); Color: Grey with slight greenish/white speckling; Luster: Dull/Sub-vitreous; Structure: Foliated with fine mineral banding; Specific Gravity: 2.7-3.2
Formation & geological history
Formed through high-grade regional metamorphism of igneous or sedimentary protoliths. These stones are usually tumbled and smoothed by high-energy fluvial (river) or glacial transport over thousands of years.
Uses & applications
Used primarily in landscaping, decorative masonry, construction aggregate, and as 'river rock' for drainage systems.
Geological facts
River stones are geological time travelers; the smoothness is the result of 'abrasion,' where the stone strikes others in water currents, removing all sharp edges over vast distances.
Field identification & locations
Identify in the field by its rounded, smooth 'toasted' texture and faint mineral stripes (foliation). Common in glacial till and active or ancient riverbeds worldwide.
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