metamorphic
Unakite
Epidotized Granite
Hardness: 6-7 on Mohs scale; Color: Mottled green, pink, and gray; Luster: Dull to vitreous; Crystal Structure: Monoclinic (epidote component) and Trigonal (quartz component); Cleavage: None/Indistinct; Specific Gravity: 2.85-3.20.
- Hardness
- 6-7 on Mohs scale
- Color
- Mottled green, pink, and gray
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Mottled green, pink, and gray; Luster: Dull to vitreous; Crystal Structure: Monoclinic (epidote component) and Trigonal (quartz component); Cleavage: None/Indistinct; Specific Gravity: 2.85-3.20.
Formation & geological history
Formed through the hydrothermal metamorphism of granite, where plagioclase feldspar is replaced by epidote. Usually associated with Precambrian orogenic events.
Uses & applications
Used extensively in jewelry as beads or cabochons, for carvings, as various decorative architectural stones, and as a popular semi-precious stone for lapidary collectors.
Geological facts
Named after the Unaka Range in the Blue Ridge Mountains of the United States (North Carolina and Tennessee) where it was first discovered. It is often found as river pebbles.
Field identification & locations
Identifiable by its unique 'pistachio green' (epidote) and 'salmon pink' (orthoclase) mottled appearance. In the field, look for these distinctive colors in rounded pebbles in riverbeds or glacial outwashes.
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