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Hajar | all galleries >> Mineral Galleries >> Midlands Minerals >> Derbyshire Minerals > Calcite, rare "axehead" twin, 4 cm. Bonsal Moor, Derbyshire, UK. 1981 find.(twin plane {01.2})
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27-JUN-2013

Calcite, rare "axehead" twin, 4 cm. Bonsal Moor, Derbyshire, UK. 1981 find.(twin plane {01.2})

"Opencast fluorspar extraction near Moor Farm, about 1.4 km southeast of Winster, exposed a large cavity (about 1 metre deep by 0.5 metres wide), at the southern end of the workings. An area about 30x30 cm square, on the eastern wall of the cavity, revealed axe-head twin crystals of calcite in clay. The cavity was lined with a thick layer of chalky white to yellow baryte, about 4 cm thick, with a botryoidal surface, and partially filled with two distinct types of clay, one quite coarse and crumbly and the other more like 'Plasticene' in texture. Of the initial find, only six crystals were recovered in a completely undamaged condition, from a total of about 30 collected. The calcite twins ranged in size from about 2.5x2.5x1.5 cm to 7.5x5x4 com, and became much sought after by Collectors (Rust, 1981)." Roy Starkey, 2018, Minerals of the English Midlands.

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