SCHALENBLENDE
Samples of ÒschalenblendeÓ (Òshell oreÓ) are
quite striking for their brassy and silvery metallic colors mixed with brown
and yellow. Schalenblende is a zinc-lead ore consisting of botryoidal
crusts of brownish-colored sphalerite (zinc sulfide - (Zn,Fe)S),
yellowish-colored wurtzite (zinc sulfide - (Zn,Fe)S), brassy-colored pyrite/marcasite
(iron sulfide - FeS2), and silver-colored galena (lead
sulfide - PbS). In the pictures of the polished specimen below, the dark
gray patches are galena - they look bright silver when tilted in the
light. Because of the high galena content, schalenblende samples are
remarkably heavy for their size.
Locality:
Pomorzany Mine, Olkœsz, Bytom (Beuthen) District, ~40 km northwest of Krakow (a.k.a.
Krakau; a.k.a. Cracow), Upper Silesia, southern Poland (~50¡ 18Õ North,
~19¡ 33Õ East).
Origin:
published research on schalenblende material indicates that mineralization was
from a sulfide gel or colloidal dispersion. Crystallization took place
during the early Early Cretaceous, at about 135 million years (= Valanginian
Stage or Hauterivian Stage, depending on which geologic time scale one
uses). This schalenblende occurrence is hosted in epigenetic dolosparites
of the upper Lower Muschelkalk Formation (Middle Triassic).
Schalenblende (12.3 cm across) from the Cretaceous of Poland, with galena
(silvery-black), pyrite/marcasite (grayish-gold), sphalerite (dark brown), and
wurtzite (pale yellow).