Contribution
Mineralogical data on cylindrite and incaite
Makovicky, Emil
Neues Jahrbuch für Mineralogie - Monatshefte Jg. 1974 Heft 6 (1974), p. 235 - 256
12 références bibliographiques
publié: Aug 27, 1974
DOI: 10.1127/njmm/1974/1974/235
ArtNo. ESP156197406001, Prix: 19.00 €
Abstract
The group of cylindrite minerals consists of cylindrite, incaite (a new mineral) and Sn-rich as well as Pb-rich lamellar phases. These complex sulfides of Pb (Ag), Sn, Sb and Fe are composed of two types of incommensurable alternating layers: pseudotetragonal MeS (Me = Pb, Sn, Ag, Fe) and pseudohexagonal MeS2 (Me = Sn), both of them corrugated by steps, containing Sb and Fe. The two sets of layers have lattices of their own, each with a pronounced sublattice (a pseudotetragonal A-centered subcell with b = 5.8 Å, c = 5.8 Å and an orthohexagonal A-centered subcell with b = 3.7 Å, c = 6.3 Å). The α-axes of the two incommensurable sublattices represent the thickness of a pair composed of one pseudohexagonal and one pseudotetragonal structural layer and are common to both components. The chemical formula of cylindrite is Pb267.5Ag4.5Sn354Sb154 Fe74S1214, with a layer-pair thickness (the α-dimension) of 11.7 Å; that of incaite is Pb331Ag33Sn368.5Sb202Fe79S1344, with a layer-pair thickness of 17.3 Å. Incaite forms oriented replacement bodies in cylindrite from Poopó, Bolivia. The optical properties and X-ray crystallography of incaite are described and compared to those of cylindrite.
Mots-clefs
Cylindrite • incaite • new mineral data • crystal chemistry