bloomfieldite

Bloomfieldite is a rare mineral, a hydrous copper oxalate. Its chemical formula is Cu2(C2O4)(OH)2. It is typically found in arid environments, often associated with copper deposits. Bloomfieldite is characterized by its bright blue to greenish-blue color and a vitreous to dull luster. It usually forms as small, acicular or prismatic crystals, often appearing as crusts or powdery aggregates.

The mineral was first discovered in the late 1970s in the Bloomfield mine, located in the Big Indian district of San Juan County, Utah, USA. This discovery led to its official naming. It is a relatively soft mineral, with a Mohs hardness of 2 to 3, and it is somewhat brittle. Bloomfieldite is not soluble in water but can be attacked by acids.

Its formation is believed to be a secondary process, occurring through the interaction of copper-bearing solutions with organic matter, specifically oxalic acid, which is a product of the decomposition of plant material. This paragenesis makes it a mineral of interest to geologists studying weathering processes and the biogeochemistry of copper deposits. Due to its rarity and small crystal size, bloomfieldite is not of significant economic importance but is collected by mineral enthusiasts and researchers for its unique composition and occurrence.