metamorphic
Unakite
Epidotized Granite
Hardness: 6-7 (Mohs); Color: Mottled green (epidote), pink (orthoclase feldspar), and clear/grey (quartz); Luster: Vitreous to dull; Crystal structure: Monoclinic/Triclinic; Cleavage: Poor/Common; Specific Gravity: 2.55-2.85.
- Hardness
- 6-7 (Mohs)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 (Mohs); Color: Mottled green (epidote), pink (orthoclase feldspar), and clear/grey (quartz); Luster: Vitreous to dull; Crystal structure: Monoclinic/Triclinic; Cleavage: Poor/Common; Specific Gravity: 2.55-2.85.
Formation & geological history
Formed through the hydrothermal alteration of granite where plagioclase feldspar is replaced by epidote. This metamsomatic process typically occurs in deep crustal environments during mountain-building events.
Uses & applications
Used primarily as a decorative stone, in lapidary work for cabochons, beads, and carvings, and occasionally as architectural stone or floor tiles.
Geological facts
Unakite was first discovered in the Unaka Range of the Blue Ridge Mountains in North Carolina, USA. It is considered a semi-precious gemstone and is the state rock of Virginia.
Field identification & locations
Identify by its distinct 'pistachio' green and salmon pink mottling. Commonly found in riverbeds and glacial tilts in the Appalachian Mountains and the Great Lakes region. Look for the absence of significant dark ferromagnesian minerals.
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