TY - JOUR
T1 - Heklaite, KNaSiF6, a new fumarolic mineral from Hekla volcano, Iceland
AU - Garavelli, Anna
AU - Balic Zunic, Tonci
AU - Mitolo, Donatella
AU - Acquafredda, Pasquale
AU - Leonardsen, Erik
AU - Jakobsson, Sveinn Peter
PY - 2010/2/1
Y1 - 2010/2/1
N2 - Heklaite, with the ideal formula KNaSiF6, was found among fumarolic encrustations collected in 1992 on the Hekla volcano, Iceland. Heklaite forms a fine-grained mass of micron- to sub-micron-sized crystals intimately associated with malladrite, hieratite and ralstonite. The mineral is colourless, transparent, non-fluorescent, has a vitreous lustre and a white streak. The calculated density is 2.69 g cm-3. An SEM-EDS quantitative chemical analysis shows the following range of concentrations (wt.%): Na 11.61-12.74 (average 11.98), K 17.02-18.97 (average 18.29), Si 13.48-14.17 (average 13.91), F 54.88-56.19 (average 55.66). The empirical chemical formula, calculated on the basis of 9 a.p.f.u., is Na 1.07K0.96Si1.01F5.97. X-ray powder diffraction indicates that heklaite is orthorhombic, space group Pnma, with the following unit-cell parameters: a = 9.3387(7) Å, b = 5.5032(4) Å, c = 9.7957(8) Å, V = 503.43(7) Å3, Z = 4. The eight strongest reflections in the powder diffraction pattern [d in Å (I/I 0) (hkl)] are: 4.33 (53) (102); 4.26 (56) (111); 3.40 (49) (112); 3.37 (47) (202); 3.34 (100) (211); 2.251 (27) (303); 2.050 (52) (123); 2.016 (29) (321). On the basis of chemical analyses and X-ray data, heklaite corresponds to the synthetic compound KNaSiF6. The name is for the type locality, the Hekla volcano, Iceland.
AB - Heklaite, with the ideal formula KNaSiF6, was found among fumarolic encrustations collected in 1992 on the Hekla volcano, Iceland. Heklaite forms a fine-grained mass of micron- to sub-micron-sized crystals intimately associated with malladrite, hieratite and ralstonite. The mineral is colourless, transparent, non-fluorescent, has a vitreous lustre and a white streak. The calculated density is 2.69 g cm-3. An SEM-EDS quantitative chemical analysis shows the following range of concentrations (wt.%): Na 11.61-12.74 (average 11.98), K 17.02-18.97 (average 18.29), Si 13.48-14.17 (average 13.91), F 54.88-56.19 (average 55.66). The empirical chemical formula, calculated on the basis of 9 a.p.f.u., is Na 1.07K0.96Si1.01F5.97. X-ray powder diffraction indicates that heklaite is orthorhombic, space group Pnma, with the following unit-cell parameters: a = 9.3387(7) Å, b = 5.5032(4) Å, c = 9.7957(8) Å, V = 503.43(7) Å3, Z = 4. The eight strongest reflections in the powder diffraction pattern [d in Å (I/I 0) (hkl)] are: 4.33 (53) (102); 4.26 (56) (111); 3.40 (49) (112); 3.37 (47) (202); 3.34 (100) (211); 2.251 (27) (303); 2.050 (52) (123); 2.016 (29) (321). On the basis of chemical analyses and X-ray data, heklaite corresponds to the synthetic compound KNaSiF6. The name is for the type locality, the Hekla volcano, Iceland.
U2 - 10.1180/minmag.2010.074.1.147
DO - 10.1180/minmag.2010.074.1.147
M3 - Journal article
SN - 0026-461X
VL - 74
SP - 147
EP - 157
JO - Mineralogical Magazine
JF - Mineralogical Magazine
IS - 1
ER -