Strunz classification 9.CO.10 Space group R3m | Crystal system Trigonal | |
Category Silicate mineral, Cyclosilicate Formula
(repeating unit) Na12Sr3Ca6Fe3Zr3NbSi25O73)(O,OH,H2O)3Cl2 (original form) Crystal class Ditrigonal pyramidal (3m)
H-M symbol: (3m) | ||
Taseqite is a rare mineral of the eudialyte group, with formula Na12Sr3Ca6Fe3Zr3NbSiO(Si9O27)2(Si3O9)2(O,OH,H2O)3Cl2. The formula given is derived from the original one and shows a separate silicon at the M4 site, basing on the nomenclature of the eudialyte group. Taseqite, khomyakovite and manganokhomyakovite are three group representatives with species-defining strontium, although many other members display stronium diadochy. Both stronium (N4Sr) and niobium (M3Nb) are essential in the crystal structure of taseqite. When compared to khomyakovite, taseqite differs in niobium- and chlorine-dominance.
Occurrence and association
Taseqite's type locality is the Taseq slope located in the Ilimaussaq complex, Greenland - hence its name. At the type locality taseqite occurs in albitite veins, together with aegirine, analcime, catapleiite, ferrobustamite, hemimorphite, pectolite (silicates); ancylite-(La), calcite, dolomite, strontianite (carbonates); fluorapatite, and sphalerite.