Semseyite with Siderite

specimen number:
2312407

location:
Herja mine, Maramures Co., Romania

description:
A superb example for the species with metallic crystals of semseyite in a grouping almost 3.0 cm across set on matrix with siderite. In very good condition. Sphalerite is present as well. At one time the specimen was in the collection of Wolfgang Henkel.

The Herja Mine, historically known as Kisbanya and located in the Maramures County of Romania, is a legendary underground mining district with operations dating back to medieval times and expanding heavily through the 19th and 20th centuries. Geologically, the deposit is situated within the Neogene volcanic arc of the Inner Carpathians, featuring complex hydrothermal vein systems hosted in volcanic and sedimentary rocks driven by extensive magmatic activity. Mineralogically, Herja is world-famous among collectors and museums for producing some of the finest epithermal ore specimens ever found, most notably brilliant, razor-sharp crystals of stibnite, berthierite, quartz, and various sulfides that display exceptional crystal size and metallic luster.

Semseyite is an uncommon lead antimony sulfosalt mineral. First described in 1881 by Hungarian mineralogist Jozsef Krenner based on material from Baia Sprie, Romania, it was named in honor of the Hungarian aristocrat and mineral collector Andor von Semsey. Geologically, semseyite typically forms in mid-temperature hydrothermal veins, often associated with other sulfides and sulfosalts like sphalerite, galena, jamesonite, and pyrite. Mineralogically, it crystallizes in the monoclinic system and is characterized by dark gray to metallic steel-black tabular or elongated prismatic crystals that frequently form rosette-like or radiating aggregates, with world-class specimens historically originating from the famous mines of Romania.

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