Fluorite

This superb miniature Fluorite is from The Bull Vein at Lady Annabella mine, close to the village of Eastgate in the Weardale Valley. The Bull Vein was the main feeder-conduit for the circulating hydrothermal fluids in this part of the quarry, with many resulting mineralised pockets developing in its proximity. It has been observed in other Weardale mines, Rogerley and Diana Maria for example, that although yellow Fluorite is relatively scarce, when it does occur it is usually within the vein rather than the metasomatic flats. This specimen is dominated by a beautiful 2.2 x 1.8 x 1.8 cm elongated Fluorite cubic crystal with a much smaller interpenetrant twin, both are gemmy and nestle on a bed of darker pale-yellow rimmed smoky grey Fluorite as single cubic crystals. The twin is lemon-yellow, although it picks-up darker accents from the surrounding crystals and matrix to produce a complex shift of smoky-yellows as the specimen is rotated. Under LWUV the entire specimen is a mixture of bright whitish-lavender and darker lilac. Fascinating, aesthetic and splendid!

The Lady Annabella mine began specimen recovery operations in July 2020 within the former Eastgate Quarry, previously known as the Blue Circle Cement Quarry. This quarry began in the early 1960s, working an exposure of the Great Limestone, a major formation of Carboniferous age (Pendleian Substage), found across much of Northern England. Following uplift and fracturing, subsequent Fluorite mineralisation pervaded this area of County Durham, in the form of sub-vertical veins and near-horizontal metasomatic flats. Metasomatism is the chemical alteration of rock by hydrothermal fluids. Over the past 55 years, Fluorite from this quarry has become famous amongst collectors for its wide range of colours, colour variations and zonation. In just its first five months of operation, the Lady Annabella mine has produced a magnificent range of Fluorite specimens, many of which are colour variants and mixtures never before seen at this locality, nor even in the other famous mines throughout the Weardale Valley.