Mineralogical and crystal-chemical descriptions are provided for two end-members of the new Group 5 introduced by Leake et al. (2004) in the nomenclature of amphiboles. This new classification scheme recognizes the occurrence of compositions with B-site populations intermediate between (Ca,Na) amphiboles and (Mg,Fe,Mn,Li) amphiboles. Its implications for the classification and nomenclature of Li-rich amphiboles are also discussed in this paper. Holotype ferri-ottoliniite [ideally A B(NaLi) C(Mg3Fe23+) Si8 O22 (OH)2] has a = 9.535(3), b = 17.876(6), c = 5.294(2) A, ?À = 102.54<(1), V = 880.9 A3, and unit formula A(K0.07Na0.38)B(Na0.70Li1.24Ca0.06)C(Mg1.35Fe2+0.92Mn2+0.13Zn0.31Fe3+ 1.71Al0.10Ti0.06Li0.42) Si8O22 (OH1.51F0.47). Holotype ferriwhittakerite [ideally ANa B(NaLi) C(Mg2Fe2 3+Li) Si8 O22 (OH)2] has a =9.712(9), b = 17.851(23), c = 5.297(2) A, ?À = 103.63<(5), V = 892.5 A3, and unit formula A(K0.13Na0.64)B(Na1.27Li0.62Ca0.11) C(Mg1.47Fe2+0.58Mn2+0.12Zn0.40Fe3+1.48Al0.10Ti0.12Li0.73) Si8 O22 (OH1.30F0.72). The root names have been chosen to acknowledge the contribution given to crystal-chemical studies of minerals, and particularly of amphiboles, by L. Ottolini (Pavia, Italy) and E.J.W. Whittaker (Oxford, U.K.).
Ferri-ottoliniite and ferriwhittakerite, two new end-members of the new Group 5 for monoclinic amphiboles.
Oberti R;
2004
Abstract
Mineralogical and crystal-chemical descriptions are provided for two end-members of the new Group 5 introduced by Leake et al. (2004) in the nomenclature of amphiboles. This new classification scheme recognizes the occurrence of compositions with B-site populations intermediate between (Ca,Na) amphiboles and (Mg,Fe,Mn,Li) amphiboles. Its implications for the classification and nomenclature of Li-rich amphiboles are also discussed in this paper. Holotype ferri-ottoliniite [ideally A B(NaLi) C(Mg3Fe23+) Si8 O22 (OH)2] has a = 9.535(3), b = 17.876(6), c = 5.294(2) A, ?À = 102.54<(1), V = 880.9 A3, and unit formula A(K0.07Na0.38)B(Na0.70Li1.24Ca0.06)C(Mg1.35Fe2+0.92Mn2+0.13Zn0.31Fe3+ 1.71Al0.10Ti0.06Li0.42) Si8O22 (OH1.51F0.47). Holotype ferriwhittakerite [ideally ANa B(NaLi) C(Mg2Fe2 3+Li) Si8 O22 (OH)2] has a =9.712(9), b = 17.851(23), c = 5.297(2) A, ?À = 103.63<(5), V = 892.5 A3, and unit formula A(K0.13Na0.64)B(Na1.27Li0.62Ca0.11) C(Mg1.47Fe2+0.58Mn2+0.12Zn0.40Fe3+1.48Al0.10Ti0.12Li0.73) Si8 O22 (OH1.30F0.72). The root names have been chosen to acknowledge the contribution given to crystal-chemical studies of minerals, and particularly of amphiboles, by L. Ottolini (Pavia, Italy) and E.J.W. Whittaker (Oxford, U.K.).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
