Quartz after Calcite with Galena

specimen number:
2312180

location:
Turt Mine, Satu Mare Co., Romania

description:

A double terminated cluster of what were once calcite crystal 7.5 cm in length, these now replaced by crystalline quartz and set up on a matrix of galena. In terrific condition.

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.

Pseudomorphs occur when one mineral replaces another while preserving the original crystal shape. A classic example is quartz after calcite, where quartz gradually dissolves or replaces an existing crystal of calcite. As the replacement happens, the incoming silica takes on the exact geometric form of the original calcite crystal. This results in a specimen that has the internal composition of quartz but the external crystal habit of calcite.

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