Mineral Species: Maxwellite

Chemical Formula: NaFe3+(AsO4)F

Chemical Name: Sodium Iron Arsenate Fluoride

Mineral Class: Arsenate

Mineral Notes: Maxwellite is a very rare mineral formed in miarolitic cavities in rhyolite adjacent to high-temperature veins in hydrothermal tin deposits. It forms two series, with Durangite, and with Tilasite. It is named after Charles Henry Maxwell (1923– ), geologist with the U.S. Geological Survey, who studied the Taylor Creek District. It was first approved by the IMA in 1987.

Description: A grey matrix containing a few small grains of red Maxwellite. These are partially embedded in the matrix but have good form. However their apperance is only best seen under magnification.

Location: Squaw Creek Tin Mine, Sierra Co., New Mexico, USA (Type Location).