Original paper
Epistolite from the Ilímaussaq alkaline complex in South Greenland
Karup-Møller, S.
Neues Jahrbuch für Mineralogie - Abhandlungen Band 155 Heft 3 (1986), p. 289 - 304
19 references
published: Nov 27, 1986
DOI: 10.1127/njma/155/1986/289
ArtNo. ESP154015503004, Price: 29.00 €
Abstract
Epistolite is a common low temperature mineral found in hydrothermal veins, pegmatites, arfvedsonite lujavrite, MC-lujavrite and naujaite in the Ilimaussaq complex in South Greenland. In many localities epistolite contains an unidentified submicroscopic phase. The average total chemical composition of epistolite and the unidentified phase is: (Na1.33K0.03Ca0.13Zn0.05Mg0.01)Σ1.55(Nb1.03Ti0.50Fe0.01Mn0.01)sub>Σ1.55O1.00(OH,F)0.78 (Si2.00O7.00)+0.08Na3PO4+nH2O. The following ranges (ppm) in trace elements contents were recorded (X-ray fluorescence) on material from four localities: Pb = 10-180, Sn = 60-1220, Zn = 60-8700, Zr = 230-670, Rb = 71-450, Sr = 53-480, Y = 18-160, Ta = 360-5220, Th = 10-90, Cl = 230-1870 and S = 1430-5470. Epistolite has the following cell dimensions (Weissenberg and Precession studies): a = 5.55 Å, b = 7.16 Å, c = 12.1 Â, α 103.47°, β = 96.00° and γ = 88.60°. The cell dimensions of the unidentified phase is: a = 5.42 Å, b = 7.13 Å, c = 13.02 Å, α = 96.04, β = 96.44 and γ = 89.32. It is characterised by a superstructure caused by a doubling of the a-cell dimension. Debye-Scherrer powder data, infrared and thermal data are listed. Two epistolite varieties with anomalous chemicals compositions are described. Alteration of epistolite has resulted in the formation of nenadkevichite.
Keywords
Epistolite • Ilìmaussaq intrusion • thermal analysis • microprobe analysis • X-ray powder diffraction (Guinier) • lattice constant • infrared spectrum • element correlation • chemical composition • trace element analysis • Greenland