Unakite

Generally, unakite is interpreted to be a metamorphic rock created by the hydrothermal alteration of either granite, granodiorite, or charnockite. It is argued that the epidote in unakite was created by the alteration of either mafic minerals; or some combination of these minerals by hydrothermal fluids. It is also possible that some of the epidote is the result of direct precipitation from hydrothermal fluids. Most commonly, unakite occurs as comparatively small and restricted bodies in granite and granodiorite. Typically, these bodies are not larger than in any dimension. In these granitoids, unakite also occurs as veins, dike-like bodies, lenses, irregular masses, or combinations of these. Where the lava flows of the Neoproterozoic Catoctin Formation directly overlie it, the dark-greenish-gray charnockite is typically bleached light gray due to the recrystallization of its plagioclase and alkali feldspar. Along joints, the migration of hydrothermal fluid induced by heat from the overlying lava has altered the charnockites to unakite. Overall, unakite in Blue Ridge region is associated with either Neoproterozoic extrusion of lavas of the overlying Catoctin Formation; enhanced fluid flow associated with fault zones; or local effects of regional Paleozoic metamorphism. ==Distribution==

The distribution of unakite is not precisely known. In part, this lack of knowledge it is due to inconsistencies in how unakite is defined and inconsistent classification of it under other names. It occurs in at least 30 locations in the United States including a few places west of the Mississippi River. Although found exposed in roadcuts, crush stone pits, and other excavation in the Blue Ridge region, high quality unakite is also found in the stream beds as rolled, well-rounded stones as in the Rose River, northwest of Syria, in Madison County, Virginia. The stones have a rusty surface experience and vary in size from cobbles to boulders. When collecting in the Blue Ridge region, it must be remembered that unakite occurs in national and state parks in which, of course, rock collecting is prohibited by law. Rock hunting is permitted in national forests, except in certain designated areas. Outside of the parks, the state and national forests, the land is all privately owned, and land owner permission is required for collecting, even if the land is rugged and mountainous and seemingly deserted. In the Midwest, unakite of unknown quality has also been reported from the Waupaca adamellite from Waupaca County, Wisconsin. Finally, in the western United States, unakite has also been reported from Teller County, Colorado and Bernalillo County, New Mexico. Unakite is listed by Manutchehr-Danai, without any accompanying documentation, as having been found in Zimbabwe, Ireland, and South Africa. ==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. ==See also==