Quartz after Calcite with Barite

specimen number:
2312254

location:
Androvo Mine, Erma Reka, Smolyon, Bulgaria

description:
Colorless tabular gemmy crystals of barite measuring to 2.3 cm in size across the top of a crystallized cluster of what was once calcite, this now mostly replaced by crystallized quartz. Unique and in good condition.

The Androvo mine, located near the village of Erma Reka in the Smolyan Province of southern Bulgaria (within the Zlatograd region), is part of the southern sector of the wider Madan ore field. Modern industrial mining operations in this area expanded significantly during the mid-20th century, particularly ramping up from the 1950s onward as part of regional state-backed efforts to extract vital base metals. Geologically, the deposit is hosted within the complex metamorphic and tectonic framework of the Rhodope Mountains. It consists primarily of hydrothermal vein and metasomatic ore bodies formed by the circulation of mineralizing fluids, yielding significant concentrations of lead and zinc minerals such as galena and sphalerite, alongside associated sulfides like pyrite and chalcopyrite.

Pseudomorphs involving quartz after calcite occur when silica-rich solutions replace original calcite crystals while preserving their external form. As the calcium carbonate gradually dissolves and is substituted by quartz, the resulting specimen retains the exact geometric shape of the original mineral. These unique pieces are often collected as hollow or solid quartz casts that reveal the historical presence of the earlier calcite.

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