Innesite

Innesite is a rare phosphate mineral with the chemical formula Ca2Mn7(PO4)6 · 6H2O. It is a member of the inesite group of minerals. Innesite typically occurs as prismatic crystals and can be found in various shades of yellow, orange, and brown. It is known for its vitreous luster. The mineral was first described in 1976 from specimens found in the Kombat Mine, Otjozondjupa Region, Namibia. The type locality remains the most significant source of innesite.

The crystal structure of innesite is complex, featuring chains of Mn(O,OH)6 octahedra linked by phosphate groups. Calcium ions and water molecules occupy the interstitial spaces within this framework. This unique structure contributes to its distinct physical properties. Innesite is relatively soft, with a Mohs hardness of 4.5 to 5. It is not a common mineral and is primarily of interest to mineral collectors and researchers due to its rarity and specific geological occurrence. It is often found associated with other manganese-bearing minerals in hydrothermal or metamorphic environments.