Original paper

QuadridavyneJ(Na,K)6Cl2][Ca2Cl2][Si6Al6O24], a new feldspathoid mineral from Vesuvius area

Bonaccrsi, Elena; Merlino, Stefano; Orlandi, Paolo; Pasero, Marco; Vezzalini, Giovanna

European Journal of Mineralogy Volume 6 Number 4 (1994), p. 481 - 488

13 references

published: Jul 27, 1994
manuscript accepted: Apr 22, 1994
manuscript received: Jan 22, 1994

DOI: 10.1127/ejm/6/4/0481

BibTeX file

ArtNo. ESP147050604009, Price: 29.00 €

Download preview PDF Buy as PDF

Abstract

Abstract A new feldspathoid mineral, quadridavyne, belonging to the davyne group, is described. It was found in the locality Ottaviano, near Napoli, southern Italy, within products of the 1906 volcanic activity of Vesuvius. It occurs as transparent, colorless, prismatic crystals, elongated [001] with hexagonal outline. Twinning (1100) is frequent. The mineral is brittle, with hardness ca. 5, dmeas= 2.335(5), dcalc = 2.354 g/cm3. Optically it is uniaxial (+), with ω = 1.529(1) and ε = 1.532(1). Its ideal chemical formula, derived from electron microprobe data, is [(Na,K)6Cl2][Ca2Cl2][(Si6Al6O24)]. Quadridavyne is hexagonal, space group P63/m, a = 25.771(6), c = 5.371(1) Å, Z = 4. The structure of quadridavyne is topologically identical to that of davyne. The major difference lies in the long-range ordering of alkaline cations (Na+ and K+) and chlorine within the open channels running along [001], resulting in the doubling of the a parameter.

Keywords

quadridavynenew mineralfeldspathoidsdavyne groupVesuvius (Italy)