Unakite

Unakite is an altered granite composed of pink orthoclase feldspar, green epidote, and generally colorless quartz.

Tumble polished unakite pebbles

Discovery

It was first discovered in the United States in the Unakas mountains of North Carolina from which it gets its name. Unakite exists in various shades of green and pink and is usually mottled in appearance.

Use

A good quality unakite is considered a semiprecious stone; it will take a good polish and is often used in jewelry as beads or cabochons and other lapidary work such as eggs, spheres and animal carvings. It is also referred to as epidotized or epidote granite.

Structure

In some of the Blue Ridge occurrences, an epidotized augen gneiss is present exhibiting foliation structures.

The dominant green epidote in unakite rocks is the metasomatic alteration product of plagioclase feldspar, while the orthoclase and quartz crystals remain unaffected.

Distribution

Unakite can be found as pebbles and cobbles from glacial drift in the beach rock on the shores of Lake Superior. It also occurs in Virginia where it is found in the river valleys after having been washed down from the Blue Ridge Mountains. Unakite is not limited to the United States, and has also been reported in South Africa, Sierra Leone, Brazil, China and Australia

Some material labeled unakite lacks the feldspar and is more properly called epidosite, and is also used as beads and cabochons.

gollark: TLC does three bits a cell, so you get 2³ = 8 voltage levels, etc. - you trade off endurance and speed for density.
gollark: The issue with it is that the flash memory wears down in some way after a bunch of program/erase cycles, so it has trouble reading/writing accurately or something, and this is a greater problem for MLC than SLC because it has to read finer gradations.
gollark: I mean, yes, the naming is weird.
gollark: MLC is two bits a cell, so it has to distinguish *four* voltage levels. This means you get twice the density.
gollark: SLC flash stores only one bit per cell, so it needs to distinguish two voltage levels.

References
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