metamorphic
Unakite
Unakite (Altered Granite composed of Orthoclase KAlSi3O8, Epidote Ca2(Al, Fe)3(SiO4)3(OH), and Quartz SiO2)
Hardness: 6-7 (Mohs scale); Color: Mottled green, pink, and gray; Luster: Vitreous to dull; Crystal Structure: Monoclinic/Trigonal (as a composite rock); Cleavage: Irregular fracture; Specific Gravity: 2.55 - 2.85
- Hardness
- 6-7 (Mohs scale)
- Color
- Mottled green, pink, and gray
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Mottled green, pink, and gray; Luster: Vitreous to dull; Crystal Structure: Monoclinic/Trigonal (as a composite rock); Cleavage: Irregular fracture; Specific Gravity: 2.55 - 2.85
Formation & geological history
Formed through the hydrothermal alteration of granite where plagioclase feldspar is replaced by epdiote. It originates in metamorphic environments and is often associated with the Grenville Orogeny (approx. 1 billion years old).
Uses & applications
Used primarily as a decorative stone, in lapidary work for cabochons and beads, architectural trim, and as a popular stone for metaphysical practitioners and crystal collectors.
Geological facts
It was first discovered in the Unaka Range of the Appalachian Mountains in North Carolina/Tennessee, USA, for which it is named. It is the unofficial state rock of Virginia.
Field identification & locations
Identify by its unique 'pistachio green' and 'salmon pink' mottled appearance. It is commonly found in riverbeds and beaches along Lake Superior and across the Blue Ridge Mountains. In the field, look for the absence of dark mica which distinguishes it from standard granite.
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