Natural specimen of triple solid solution ettringite–thaumasite–chromate-ettringite

Author: Drebushchak V.   Seryotkin Yu   Kokh Svetlana   Sokol Ella  

Publisher: Springer Publishing Company

ISSN: 1388-6150

Source: Journal of Thermal Analysis and Calorimetry, Vol.114, Iss.2, 2013-11, pp. : 777-783

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

Three natural minerals of ettringite group were investigated by TG to refine their chemical composition. Two samples are ettringite Ca5.97Mg0.01Sr0.02Al1.99Cr0.01(SO4)3(OH)12·23.7H2O and bentorite Ca5.99Mg0.01Cr1.95Al0.01Si0.03(SO4)2.82·(CO3)0.20(OH)12·19.4H2O, but the third one Ca5.99Na0.01Al1.38Si0.62(SO4)2.49·(CrO4)0.36·(CO3)0.46(OH)12·15.8H2O has found to be a solid solution among ettringite, thaumasite, and chromate-ettringite, not registered yet as a new mineral species. Similar phase is well known in concrete formed with Cr6+ admixture, but is found for the first time as a natural compound. X-ray single-crystal investigation allowed us to refine the structure and support substitution (SO4)2− ↔ (CrO4)2− in natural minerals of ettringite group.