Fluorite

The Sherry Twins Pocket at Lady Annabella mine has produced many outstanding specimens of sherry-coloured Fluorite which exhibit a good daylight fluorescence, a property not widely observed in the Lady Annabella Fluorites. With crystals measuring 3.5 x 2.8 x 2.4 cm and 3.8 x 3.3 x 2.2 cm, this ex-matrix interpenetrant twin grades from quite gemmy transparent light sherry-brown Fluorite adjacent to the crystal faces down to milky-white translucent Fluorite with opaque areas at the crystal roots. Occasional snowflake-like bursts of milky-white Fluorite occur within the sherry zones. In sunlight the specimen has a rich warm mauve daylight fluorescence. Under LWUV the crystal outer edges fluoresce bright intense lavender forming an outline framework while within this the face centres emit a deep lilac fluorescence.

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.