Charoite

This sample of charoite is displayed in the Smithsonian Museum of Natural History. Charoite is an example of the complexity of the silicate minerals which comprise the bulk of the Earth's crust. Its composition is listed as (K,Na)₅(Ca,Ba,Sr)₈Si₁₈O₄₆(OH,F).nH₂0. In addition to the typical silicate constituents, this one has barium, strontium and fluorine . This sample is about 25x18 cm and is from Aldan, Yakutiya, Russia.