Chalcopyrite, Dolomite

Here's a specimen showing several small metallic brown-brassy chalcopyrite crystals perched on dolomite-rich brecciated matrix from the Whitespots–Conlig Mines (Whitespots–Conlig Vein), Conlig, County Down, Northern Ireland. The chalcopyrite crystals are modest in size but well defined, displaying the metallic lustre typical of the species and illustrate the sulfide mineralization characteristic of this historic locality.

The Whitespots–Conlig mining district was one of the largest lead-producing areas in Ireland during the early nineteenth century, yielding up to 15,000 tons of refined lead along with smaller amounts of copper and silver. Mineralization occurs in hydrothermal veins and dolomite-cemented breccias hosted by Silurian greywackes and shales. Galena was the principal ore mineral, accompanied by chalcopyrite, sphalerite, and pyrite with gangue minerals including dolomite, calcite, quartz, and barite. The locality is also notable for producing harmotome, a rare barium zeolite and the only known occurrence of that species in Northern Ireland. This specimen comes from the international collection of Robert Yeoman.