metamorphic
Greenschist / Migmatite
Regional Metamorphic Complex (Facies: Greenschist to Amphibolite)
Hardness: 5-7 Mohs; Color: Muted greens, grey-black, and salmon pink; Luster: Pearly to Vitreous; Crystal Structure: Generally microcrystalline with visible phaneritic bands of feldspar; Cleavage: Good in mica-rich planes; Specific Gravity: 2.6 - 3.0
- Hardness
- 5-7 Mohs
- Color
- Muted greens, grey-black, and salmon pink
- Luster
- Pearly to Vitreous
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Physical properties
Hardness: 5-7 Mohs; Color: Muted greens, grey-black, and salmon pink; Luster: Pearly to Vitreous; Crystal Structure: Generally microcrystalline with visible phaneritic bands of feldspar; Cleavage: Good in mica-rich planes; Specific Gravity: 2.6 - 3.0
Formation & geological history
Formed through regional metamorphism of basaltic or sedimentary protoliths under high pressure and moderate temperatures (300-450°C). The pinkish bands suggest partial melting or potassium feldspar injection common in higher-grade metamorphic zones.
Uses & applications
Used primarily in construction as crushed stone or decorative facing. Occasionally used in landscaping or by amateur lapidaries for polishing into cabochons if the mineral coloring is vibrant.
Geological facts
Rocks like this often display 'foliation', which are parallel layers formed when pressure aligns minerals. The green color is usually derived from chlorite, epidote, or actinolite, minerals that thrive in low-to-medium grade metamorphic conditions.
Field identification & locations
Identify in the field by the distinct layering (schistosity) and the waxy, green sheen combined with hard, pink feldspar intrusions. Often found in mountain belts where tectonic plates have collided.
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