Galena after Pyrrhotite with Galena, Siderite, Chalcopyrite

specimen number:
2312184

location:
Turt Mine, Satu Mare Co., Romania

description:

A pseudo-hexagonal crystal of what was once pyrrhotite almost 4.0 cm across, this now replaced by crystallized galena. This is set on a matrix of large lustrous octahedral galena crystals. Minor siderite and chalcopyrite scattered throughout. This is in super condition and rather neat.

The Turt Mine, located in the Oas Mountains of Satu Mare County in northwestern Romania, is part of a historic metallogenic region with long-standing underground mining operations targeting base and precious metals. Geologically, the deposit is situated within the Neogene volcanic belt of the Inner Carpathians, where subvolcanic structures and complex hydrothermal vein systems cut through older formations. These fluid systems deposited concentrated pockets of lead, zinc, and copper sulfides. The mine has gained recognition among mineral collectors for producing fine specimens of galena, quartz, and distinctive pseudomorphs or crystal casts involving siderite replacing earlier carbonate minerals.

A pseudomorph is a mineral that consists of one mineral species that has replaced another while retaining the original crystal shape. A classic example is galena after pyrrhotite, where galena gradually takes the place of the original pyrrhotite crystal. During this replacement process, the internal chemical composition and crystal structure transform into galena, yet the external morphology of the resulting specimen still preserves the distinct crystal form characteristic of the earlier pyrrhotite.

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