Topic
Taseqite
About: Taseqite is a research topic. Over the lifetime, 3 publications have been published within this topic receiving 30 citations. The topic is also known as: IMA2002-055.
Papers
TL;DR: Taseqite is a new mineral species found in small cavities in a single hydrothermal, albitite vein on the top of the Taseq slope, in the northern part of the Ilimaussaq alkaline complex, South Greenland as mentioned in this paper.
Abstract: Taseqite is a new mineral species found in small cavities in a single hydrothermal, albitite vein on the top of the Taseq slope, in the northern part of the Ilimaussaq alkaline complex, South Greenland. Besides albite the associated minerals include aegirine, analcime, ancylite-(La), calcite, catapleiite, dolomite, ferrobustamite, fluorapatite, hemimorphite, pectolite, sphalerite and strontianite. Taseqite forms clusters of crystals or individual crystals ranging in size from 0.05 by 0.25 to 0.5 by nearly 3mm. The crystals show combinations of {0001}, {0001}, {1120}, {1010}, {0110}, the latter two only represented by very narrow faces, {1011}, {0112}, {0111}, {1012}, all nearly equally developed, and occasionally (0221} and {2021}; the crystals are platy on {0001}. The colour varies from clove to yellowish brown and lemon yellow; taseqite is transparent and has a vitreous lustre. The Mohs hardness is 5½; taseqite is brittle and shows fair cleavage on {0001}/{0001}. D m e a s . = 3.24(1)g/cm 3 , D c a l c . = 3.20 g/cm 3 . Taseqite is uniaxial, optically negative, with n e = 1.6378(5) and n ω = 1.6494(3) for λ = 589 nm. The infrared spectrum shows the presence of OH, H 2 O and CO 3 . The microprobe analyses gave: Na 2 O 7.71, K 2 O 0.23, CaO 8.19, SrO 13.98, MnO 3.02, FeO 3.92, Y 2 O 3 0.28, Ce 2 O 3 0.08, SnO 2 0.13, ZrO 2 9.89, HfO 2 0.32, Nb 2 O 5 4.38, Ta 2 O 5 0.24, SiO 2 41.64, Cl 1.91, H 2 O 0.59 (by stoichiometry determined from crystal structure analysis), O ≡ Cl = -0.43, total = 96.08. The empirical formula, based on 78.14 anions as found in the crystal structure analysis is: (Na 8 . 8 1 Sr 4 . 7 8 K 0 . 1 7 Ce 0 . 0 2 ) Σ 1 3 . 7 8 (Ca 5 . 1 7 Mn 0 . 5 9 Y 0 . 0 9 ) Σ 5 . 8 5 (Fe 1 . 9 3 Mn 0 . 9 2 ) Σ 2 . 8 5 (Zr 2 . 8 4 Nb 0 . 1 1 Hf 0 . 0 5 ) Σ 3 . 0 0 (Nb 1 . 0 6 Ta 0 . 0 4 Sn 0 . 0 3 ) Σ 1 . 1 3 Si 2 4 . 5 5 O 7 3 (O 1 . 6 5 OH 0 . 7 5 (H 2 O) 0 . 7 4 ) Σ 3 . 1 4 (Cl 1 . 9 1 OH 0 . 0 9 ) Σ 2 . 0 0 ; Z = 3 The ideal formula is: Na 1 2 Sr 3 Ca 6 Fe 3 Zr 3 NbSi 2 5 O 7 3 (O,OH,H 2 O) 3 Cl 2 . The strongest lines on the X-ray powder-diffraction pattern [d in A (I) (hkl)] are: 9.51 (9) (012), 3.43 (9) (131, 223), 3.19 (8) (208), 2.98 (10) (315), 2.86 (10) (404). The unit cell parameters refined from powder data are: a = 14.286(6) and c = 29.99(2) A, c: a = 2.0993, V = 5300.7 A 3 . The crystal structure was determined by single-crystal X-ray diffraction and refined to R = 0.037. Taseqite crystallizes in the trigonal system, space group R3m, a = 14.2828(6) and c = 30.0222(12) A, V = 5303.9(4) A 3 . The compatibility index 1 - Kp/Kc is equal to 0.0005, which is rated as superior. Taseqite belongs to the eudialyte group. It is primarily distinguished from other members of the group by the unique combination of dominance of Sr in N(4) and Nb in M(3).
16 citations
TL;DR: The Sushina eudialyte is characterized by low-to-negligible Fe and high Mn and Nb contents relative to most other localities as discussed by the authors, and the deuteric/hydrothermal fluids responsible for the alteration are considered as not buffered by the coexisting silicate assemblage and to be water-rich with high Na/Cl and Na/F ratios.
15 citations
TL;DR: In this paper, an eudialyte group mineral, found in pegmatites of the Odikhincha massif (the northern part of the Siberian platform), has been investigated using X-ray diffraction, IR spectroscopy, and Raman Spectroscopy.
Abstract: An eudialyte group mineral, found in pegmatites of the Odikhincha massif (the northern part of the Siberian platform), has been investigated using X-ray diffraction, IR spectroscopy, and Raman spectroscopy. The mineral is characterized by a high strontium content and a low chlorine content. It has a trigonal unit cell with the following parameters: a = 14.2700(6) A and c = 30.057(1) A; V = 5300.6(1) A3; sp. gr. R3m. The structure has been refined to R = 0.047 in the anisotropic approximation of atomic displacements using 1697F > 4σ(F). The idealized formula (Z = 3) was found to be Na12Sr2Ca6Fe
3
2+
Zr3NbSi25O72(OH,O)4Cl(Н2О)0.2. The chemical composition and structure of this mineral are close to those of taseqite; however, it differs from the holotype sample by a low chlorine content and peculiarities of cation distribution over basic structure sites. A comparative analysis of strontium-rich eudialytes has revealed their important crystallochemical feature: selective concentration of strontium in the N4 site. Thus, taseqite, along with heterophyllosilicates, may play a role of strontium concentrator in agpaitic pegmatites.
9 citations
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| Year | Papers |
|---|---|
| 2018 | 1 |
| 2012 | 1 |
| 2004 | 1 |