Freibergite on Calcite with Jamesonite inclusions

specimen number:
2312059

location:
Herja mine, Maramures Co., Romania

description:
A classic grouping of curved lustrous black calcite crystals, these with small metallic crystals of freibergite scattered sparsely throughout. In great condition. Neat combination piece for this famous old and long closed locality.

The Herja Mine, located in Maramures County, Romania, within the Baia Mare metallogenic district, is a prominent polymetallic hydrothermal vein deposit. Its geology is closely tied to Neogene post-collisional volcanism and subvolcanic intrusions, which created an extensive network of over 260 complex veins hosted within sedimentary and volcanic formations. Mining activity in the surrounding area dates back to the Middle Ages, with industrial extraction focusing heavily on lead, zinc, copper, and silver ores. The mine gained international recognition among mineral collectors for its diverse assemblage of hydrothermal minerals, including distinct stibnite clusters, sulfosalts, and rare bicolored calcite spheres. Commercial operations at the site permanently ceased in 2005, closing the underground infrastructure.

Freibergite is a complex sulfosalt mineral belonging to the tetrahedrite group, with the chemical formula generally expressed as a silver-rich copper antimony sulfide. It crystallizes in the isometric system, typically forming tetrahedral or pseudo-octahedral crystals, though it is more commonly found as massive, granular, or compact aggregates with a metallic luster and a dark steel-gray to black color. Structurally, it forms a complete solid solution series with tetrahedrite, incorporating significant and variable amounts of silver into its crystal lattice, which often makes it an important ore mineral for silver extraction. It typically occurs in hydrothermal vein deposits alongside other sulfide minerals such as galena, sphalerite, chalcopyrite, and various silver sulfosalts.

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