molybdophane

Molybdophane is a rare mineral belonging to the molybdate class, with the chemical formula (NH4)2MoO4. It was first discovered in 1845 in the Moctezuma mine, near San Luis Potosí, Mexico, and was named for its molybdenum content. Molybdophane is typically found in the oxidation zone of molybdenum-bearing deposits, often associated with other secondary molybdate minerals such as powellite and wulfenite.

The mineral crystallizes in the monoclinic system, forming prismatic crystals that can reach up to 10 centimeters in length. It is usually colorless or white, but can also exhibit shades of yellow, orange, or red due to impurities. Molybdophane has a Mohs hardness of 3.5 to 4 and a specific gravity of approximately 2.9. Its crystal structure is characterized by the presence of ammonium (NH4+) ions and molybdate (MoO4^2-) ions.

Molybdophane is not considered to be of significant economic value due to its rarity and the fact that it is primarily composed of ammonium and molybdenum, which are not highly sought-after elements. However, it is of interest to mineral collectors and researchers studying the geochemistry of molybdenum deposits. The mineral's formation is closely related to the oxidation of primary molybdenite (MoS2) and the subsequent leaching of molybdenum into the surrounding environment.