metamorphic
Unakite
Epidotized Granite
Hardness: 6-7 (Mohs scale); Color: Mottled green (epidote), pink (orthoclase), and clear/white (quartz); Luster: Vitreous to dull; Crystal structure: Monoclinic/Hexagonal mix; Specific gravity: 2.85-3.20.
- Hardness
- 6-7 (Mohs scale)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Mottled green (epidote), pink (orthoclase), and clear/white (quartz); Luster: Vitreous to dull; Crystal structure: Monoclinic/Hexagonal mix; Specific gravity: 2.85-3.20.
Formation & geological history
Unakite is formed through the hydrothermal metamorphism of granite, where plagioclase feldspar is replaced by epidote. The location near 48.8°N, 67.5°W (Gaspé Peninsula, Quebec) is highly plausible due to the region's complex Appalachian metamorphic history.
Uses & applications
Commonly used as a lapidary stone for beads, cabochons, and decorative carvings. It is also used as architectural stone and in construction aggregate.
Geological facts
Named after the Unaka Range in the Appalachian Mountains where it was first discovered. It is the state rock of Virginia and is unusual because it contains both a pink feldspar and a green mineral in an attractive mottled pattern.
Field identification & locations
Identify by the distinct 'pistachio' green and salmon pink mottling. In the field, look for river-worn pebbles showing this specific color combination. It is often found in glacial till and riverbeds throughout the Appalachian and Laurentian regions.
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