The gemstone charoite is formed by heat, pressure and the presence of certain minerals in the Chavo River Valley. It is scientifically known as Hydrated Potassium Sodium Calcium Barium Strontium Silicate Hydroxide Fluoride -- and it's made from several rock minerals contained within limestone. These include microcline feldspar, aergirine-augite and tinaksite. However, these minerals are found in small quantities compared to the large amounts of charoite in it which give its defining composition and name.
Charoite is a distinct purple color with a white marble grain. Scientists at the Gem Society are unsure why it's purple. However, the swirling marble pattern is formed from interlocking patterns formed by fibrous crystals in the stone.
Charoite is measured at between five and six on the Minerals of Hardness Scale which runs from 1 to 10. Hardness is an indication of the strength of a mineral -- diamond is the strongest at 10 and kitchen knives are rated at 5.5. Scientists measure hardness by seeing how easy one mineral is to scratch with another mineral.
Despite the fact charoite is rare and has only been discovered in the Chavo River Valley, it is an inexpensive gemstone. The Gem Society state its value at a few dollars per carat. The marble patterning and purple color do not affect it's value.
Luster is how well an object reflects light and affects how dull or shiny a mineral is. Charoite has a vitreous to pearly luster, according to the Mineral Gallery. This is true of 70 percent of minerals and means that charoite has similiar reflectiveness to glass or a shirt button.