Rapidcreekite of anthropogenic origin - &amp;rsquo;korkinoite&amp;rsquo; from burnt mine dump in the Chelyabinsk coal basin, South Urals, Russia: crystal structure refinement, thermal behavior and spectroscopic characterization

Avdontceva, Margarita S.; Золотарев, А. А.; Krivovichev, Sergey V.; Krzhizhanovskaya, Maria G.; Bocharov, Vladimir N.; Shilovskikh, Vladimir V.; Rassomakhin, M.A.

doi:10.3190/jgeosci.327

Cited by 4 publications

(2 citation statements)

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“…2À ions in the formation of the 101 gypsum contact twin law Rapidcreekite is a rare hydrated Ca-sulfate-Ca-carbonate compound (Ca 2 SO 4 CO 3 Á4H 2 O) found in association with gypsum and other carbonate minerals (Bots, 2011;Avdontceva et al, 2021). It is composed of layers of Ca-SO 4 -Ca -CO 3 with each Ca site coordinated by CO 3 , SO 4 and two H 2 O groups (Cooper & Hawthorne, 1996).…”

Section: The Role Of Comentioning

confidence: 99%

“…It is composed of layers of Ca-SO 4 -Ca -CO 3 with each Ca site coordinated by CO 3 , SO 4 and two H 2 O groups (Cooper & Hawthorne, 1996). It belongs to the orthorhombic Pbcn space group and its unit-cell parameters are a 0 = 15.49 A ˚, b 0 = 19.18 A ˚, c 0 = 6.15 A ˚, = = = 90 (Cooper & Hawthorne, 1996;Roberts et al, 1986;Avdontceva et al, 2021).…”

Section: The Role Of Comentioning

confidence: 99%

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101 contact twins in gypsum experimentally obtained from calcium carbonate enriched solutions: mineralogical implications for natural gypsum deposits

Cotellucci¹,

Otálora²,

Canals³

et al. 2023

J Appl Cryst

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Gypsum twins are frequently observed in nature, triggered by a wide array of impurities that are present in their depositional environments and that may exert a critical role in the selection of different twin laws. Identifying the impurities able to promote the selection of specific twin laws has relevance for geological studies aimed at interpreting the gypsum depositional environments in ancient and modern deposits. Here, the effect of calcium carbonate (CaCO3) on gypsum (CaSO4·2H2O) growth morphology has been investigated by performing temperature-controlled laboratory experiments with and without the addition of carbonate ions. The precipitation of twinned gypsum crystals has been achieved experimentally (101 contact twin law) by adding carbonate to the solution, and the involvement of rapidcreekite (Ca2SO4CO3·4H2O) in selecting the 101 gypsum contact twin law was supported, suggesting an epitaxial mechanism. Moreover, the occurrence of 101 gypsum contact twins in nature has been suggested by comparing the natural gypsum twin morphologies observed in evaporitic environments with those obtained in experiments. Finally, both orientations of the primary fluid inclusions (of the negative crystal shape) with respect to the twin plane and the main elongation of sub-crystals that form the twin are proposed as a fast and useful method (especially in geological samples) to distinguish between the 100 and 101 twin laws. The results of this study provide new insights into the mineralogical implications of twinned gypsum crystals and their potential as a tool to better understand natural gypsum deposits.

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Section: The Role Of Comentioning

confidence: 99%