U is for Unakite
If you have been to the Smithsonian in Washington, D.C., you may have seen or actually walked on unakite without realizing it. You will find unakite on the mall-side terrace of the Natural History Museum. Unakite is a metamorphic form of granite altered by orthoclase, epidote, and quartz. It is a strong mineral (a 6 – 7 on the Mohs scale) which makes it suitable for building although it is predominately used where aesthetics are important.
Unakite was identified in 1874 by ETSU geologist Frank Bradley. It was named after the Unaka Mountains which run along the border of North Carolina and Tennessee. It has a very distinct color pattern of greens (epidote) and pinks (orthoclase). In addition to its use in construction, it is a wonderful material for lapidary or carving work. It also polishes nicely and has no known toxicity concerns.
While discovered along the Tennessee / North Carolina border, unakite can be found in other places throughout the world. This particular piece was found in New Jersey and is on display at the Smithsonian. It gives you a good sense of using this stone for more ornate architectural purposes.
Unakite is often sold as tumbled/polished stones or pre-cut cabochons or beads. Lapidary slabs are easily available and affordable.