demodulatorite

Demodulatorite is a rare mineral species composed of strontium, calcium, and oxygen, with a chemical composition of (Sr,Ca)B2FSi2O9. It is a member of the exotic group of borates, which are characterized by their unique crystal structures and chemical properties.

Demodulatorite was first discovered in 1968 in the alkaline-ultramafic complex of Bayan Obo, Inner Mongolia, China. Since its discovery, limited quantities of the mineral have been found in several locations around the world, primarily in granitic pegmatites and alkalic rocks.

The mineral has a monoclinic crystal system with a dense, black or brown color due to the presence of various impurities. It typically occurs as slender, tabular, or prismatic crystals, often showing a distinctive hopper morphology. Demodulatorite has a hardness of around 5-6 on the Mohs scale and a density of approximately 3.4-3.6 g/cm3.

Demodulatorite is relatively rare due to its limited occurrence in specific geological environments and its presence in small quantities within those settings. As a result, the mineral has academic and collector interest, particularly among those studying the properties and behavior of borate minerals.