Calciolangbeinite, K2Ca2(SO4)3, a new mineral from the Tolbachik volcano, Kamchatka, Russia

Researchers have discovered calciolangbeinite, K2Ca2(SO4)3, a new mineral from the Tolbachik volcano in Kamchatka, Russia. This calcium-dominant analogue of langbeinite was found in sublimates at the Yadovitaya fumarole, associated with other minerals like langbeinite and hematite. Calciolangbeinite forms tetrahedral to pseudooctahedral crystals or anhedral grains, exhibiting transparency, vitreous lustre, and a Mohs' hardness of 3–3½. It is optically isotropic with a measured density of 2.68(2) g/cm³. The mineral's crystal structure, determined via single-crystal X-ray diffraction, reveals a langbeinite-type framework with disordered Ca and Mg in octahedra and SO4 tetrahedra, while potassium occupies two distinct sites. This discovery highlights the complexity of mineral formation in volcanic environments and extends knowledge of the langbeinite solid-solution series.

Pekov, I. V., Zelenski, M. E., Zubkova, N. V., Yapaskurt, V. O., Chukanov, N. V., Belakovskiy, D. I., & Pushcharovsky, D. Y. (2012). Calciolangbeinite, K₂Ca₂(SO₄)₃, a new mineral from the Tolbachik volcano, Kamchatka, Russia. Mineralogical Magazine, 76(3), 673–682. https://doi.org/10.1180/minmag.2012.076.3.16