Images
Formula: K2Ca2(SO4)3
Sulphate, langbeinite group, forms a solid solution series with
langbeinite
Crystal System: Isometric
Specific gravity: 2.68 measured, 2.74 calculated
Hardness: 3 to 3½
Streak: White
Colour: Colourless
Luminescence: Not fluorescent under UV
Environments
Metamorphic environments
Fumeroles
Localities
At Har Parsa, Hatrurim Basin, Tamar Regional Council, Southern District, Israel, calciolangbeinite has
been found in pyrometamorphic gehlenite-bearing rocks
(EJM 28, 93-103).
At the type locality, the Yadovitaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure eruption,
Tolbachik volcano, Kamchatka Krai, Russia, calciolangbeinite occurs in sublimates associated with
langbeinite, piypite,
hematite, rutile,
pseudobrookite,
orthoclase, lyonsite,
lammerite, cyanochroite
and chlorothionite. Calciolangbeinite occurs as tetrahedral
to pseudo-octahedral crystals, and as anhedral grains up to 1 mm in size, aggregated into clusters up to 2 mm across,
and forming crusts covering areas of up to 1.5 × 1.5 cm2 on the surface of volcanic
scoria. Late-stage calciolangbeinite occurs in complex epitaxial
intergrowths with langbeinite.
Calciolangbeinite is transparent and colourless with a white streak and vitreous lustre
(MM 76.3.673–682).
Calciolangbeinite-O is the low-temperature, orthorhombic,
paramorph and calciolangbeinite-C is the high-temperature,
cubic paramorph. In both high-temperature fumaroles and
pyrometamorphic rocks calciolangbeinite crystallises in the cubic modification, and during cooling its
chemical variety close to the end-member composition undergoes phase transition to calciolangbeinite-O, whereas the
magnesium-enriched varieties remain calciolangbeinite-C
(MM 86.4.557-569).
Back to Minerals