Somervillite is a mineral, specifically a borate mineral, that belongs to the rare minerals of the inderite-supergroup. It is named after Alexander Newton Somerville, an American mineral collector. Somervillite was discovered in the mid-20th century, precisely in 1955, at the Christmas Mine near Hayden, Gila County, Arizona, USA.
In terms of its physical characteristics, somervillite typically occurs as small, prismatic crystals that are light green or blue-green in color. It crystallizes in the monoclinic crystal system and can display a vitreous to resinous luster. It has a perfect cleavage along one direction, and its calculated density is approximately 2.22 grams per cubic centimeter.
Chemically, somervillite is a hydrate, containing water within its crystal structure. Its chemical formula is ideally expressed as Co( OH, O )2[B(OH)4], indicating the presence of cobalt, oxygen, and boron ions. However, the actual composition may have slight variations due to the substitution of other elements within the crystal lattice.
Somervillite is categorized as a secondary mineral, forming as a result of weathering and alteration processes that occur in borate-rich environments. It is typically found in association with minerals such as rosasite, malachite, chalcoalumite, and tyrolite. Due to its scarcity and limited occurrence, somervillite does not have significant industrial applications but is highly valued among mineral collectors and enthusiasts for its interesting crystal habits and vibrant colors.
