Boulangerite

Boulangerite is a rare mineral with the chemical formula (NH4)2Fe(SO4)2(SO3)2. It was first discovered in 1845 in the Boulanger mine in the Vosges Mountains of France, from which it derives its name. Boulangerite is typically found in the oxidation zone of sulfide-bearing deposits, often associated with other secondary minerals such as rozenite, copiapite, and halotrichite. It forms as a result of the alteration of iron sulfide minerals by atmospheric oxygen and water.

The mineral is characterized by its bright yellow to orange color, which is due to the presence of iron in its structure. Boulangerite crystals are typically prismatic or tabular, and they can grow to a significant size, although they are not as common as some other minerals. The mineral has a hardness of approximately 2.5 on the Mohs scale and a specific gravity of around 2.75. It is soluble in water and can form efflorescent crusts in arid environments.

Boulangerite is of limited economic interest due to its rarity and the fact that it is not a significant source of any valuable elements. However, it is of interest to mineral collectors and researchers due to its unique chemical composition and the conditions under which it forms. The mineral has been studied for its potential use in the removal of ammonia from wastewater, as it can absorb ammonia from solution.