dravanite

Dravanite is a rare and distinctive mineral belonging to the sulfate class, first identified in 1977 at the Dravan mine in the Kola Peninsula of Russia. It was named after its type locality, the Dravan deposit, which is known for its unique mineral assemblages. Dravanite has since been found in only a few other locations worldwide, including the Khibiny and Lovozero massifs in Russia, as well as in some volcanic environments.

Chemically, dravanite is a hydrated calcium sulfate with the formula Ca₃(SO₄)₂(OH)₂·3H₂O. It crystallizes in the orthorhombic system, forming small, tabular crystals that are typically colorless or white, though specimens may exhibit faint yellowish or grayish tints due to impurities. The mineral is transparent to translucent with a vitreous to pearly luster and exhibits a white streak. Dravanite has a Mohs hardness of approximately 3 to 3.5 and is relatively soft, making it susceptible to scratching.

Dravanite is often associated with other sulfate minerals such as gypsum, barite, and anhydrite, as well as with calcite and various rare earth minerals in alkaline pegmatites and hydrothermal veins. Its formation is typically linked to low-temperature hydrothermal processes, where sulfate-rich fluids interact with host rocks. Due to its scarcity and distinctive characteristics, dravanite is of interest to mineralogists and collectors, though it is not economically significant.

The mineral’s structure has been studied using X-ray diffraction, revealing its layered composition with sulfate groups and calcium ions arranged in a repeating pattern. Dravanite’s rarity and the limited number of known occurrences contribute to its status as a noteworthy specimen in mineral collections. Research on dravanite continues to provide insights into the conditions under which it forms and its role in hydrothermal systems.