Wolfeite

Wolfeite is a rare mineral with the chemical formula (NH4)Mn2+2(PO4)2·4H2O. It is named after the American mineralogist George D. Wolfe. Wolfeite is typically found in the oxidation zones of phosphate-bearing rocks, often associated with other secondary phosphate minerals such as variscite and phosphosiderite. It is also known to occur in the guano deposits of seabird colonies.

Wolfeite crystallizes in the monoclinic system, forming prismatic crystals that can reach up to 10 centimeters in length. The mineral is usually colorless or white, but it can also exhibit shades of yellow, brown, or green due to impurities. Its hardness on the Mohs scale is approximately 3.5, and it has a specific gravity of around 2.6.

The mineral is of interest to collectors and mineralogists due to its rarity and distinctive crystal habit. It is also studied for its potential use in the production of phosphorus-based fertilizers. Wolfeite is not considered to be a significant ore of phosphorus, but it can be a valuable source of manganese, which is an essential element in steel production.

Wolfeite was first described in 1962 from the type locality in the Santa Cruz County, Arizona, USA. It has since been reported from a few other locations worldwide, including the United Kingdom, Germany, and Japan. The mineral's rarity and the challenges associated with its identification make it a fascinating subject for mineralogical research.