metamorphic
Unakite
Unakite (Altered Granite consisting of Orthoclase KAlSi3O8, Epidote Ca2(Al,Fe)3(SiO4)3(OH), and Quartz SiO2)
Hardness: 6-7 (Mohs scale); Color: Mottled green and pink/salmon; Luster: Vitreous to dull; Crystal structure: Monoclinic (Epidote) and Triclinic (Feldspar); Cleavage: Irregular fracture; Specific gravity: 2.85-3.20
- Hardness
- 6-7 (Mohs scale)
- Color
- Mottled green and pink/salmon
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Mottled green and pink/salmon; Luster: Vitreous to dull; Crystal structure: Monoclinic (Epidote) and Triclinic (Feldspar); Cleavage: Irregular fracture; Specific gravity: 2.85-3.20
Formation & geological history
Formed through the hydrothermal alteration of granite where plagioclase feldspar is replaced by epidote. It is commonly associated with Precambrian basement rocks, though individual specimens can be much younger depending on the regional geology.
Uses & applications
Used primarily as a decorative stone, in lapidary work for cabochons and beads, architectural tiles, and as an ornamental landscaping stone. It is also a popular stone for carving figurines.
Geological facts
First discovered in the Unaka Range of North Carolina, USA, from which it derives its name. It is the state rock of Virginia. It is unique among rocks for its distinct 'Christmas-like' color combination of green and pink.
Field identification & locations
Identify in the field by its unique pink feldspar and pistachio-green epidote mottling. It is commonly found as river pebbles in areas with granitic basement rock, notably in the Blue Ridge Mountains (USA), South Africa, and Brazil.
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