Fluorite, Quartz

Frazer’s Hush Mine, Rookhope, Stanhope, County Durham, England, UK

7×6,7×5,5 cm.

Highly lustrous piece composed of glassy and gemmy pinkish magenta Fluorite, twinned by interpenetration, and partially covered with a multitude of brilliant Quartz crystals. Very interesting specimen from this classic northern England locality.

The Carboniferous rocks in the North Pennines are intersected by numerous mineral veins, often associated with the Caledonian Weardale granite. However, it is believed that the granite might not have been the primary source of heat for mineralization; instead, it could have directed heated mineralizing fluids through the Carboniferous sediments (Dunham et al., 1965). While many veins are typically just over 1m wide, there have been instances of widths exceeding 10m. The orefield displays a distinct zonation of constituent minerals, particularly among the non-metalliferous or gangue minerals.

Deposits in the central zone exhibit an abundance of fluorite (CaF2), alongside quartz, chalcopyrite (CuFeS2), galena (PbS), and sphalerite (ZnS). In the surrounding fluorite zone, a broader range of deposits is characterized by barium minerals, including baryte (BaSO4) and witherite (BaCO3), serving as the characteristic gangue. Galena and other sulphide minerals are less commonly found in this zone. The mineral zonation is interpreted as a reflection of progressively lower crystallization temperatures of mineralizing fluids as they moved outward from central ’emanative centers’ above high spots (cupolas) on the underlying Weardale Granite (Dunham, 1991). Frazer’s Grove Mine is situated above one such emanative center within the fluorite zone.

Frazer’s Grove mine is situated in the North Pennines in County Durham, UK; it consists of four mines: Frazer’s Hush, Rake Level/Firestone Incline, Grove Rake and Greencleugh. They have been formerly worked for lead (Pb-Zn orefield), but during this century only fluorite has been worked. However, due to very low fluorite prices, mining in the deep sections of Frazer’s Hush was stopped at the end of 1998. For more info