Paracelsian

minerals

tectosilicate

feldspar

metamorphic

Formula: Ba(Al2Si2O8)
Tectosilicate (framework silicate), feldspar group, monoclinic paramorph of celsian, which is also monoclinic, and hexagonal hexacelsian
Crystal System: Monoclinic
Specific gravity: 3.29 to 3.32
Hardness: 5½ to 6
Streak: White
Colour: Colourless, white, pale yellow
Luminescence: A pale pink fluorscence has been observed on one specimen from Benallt
Common impurities: Fe,Mg,Ca,Na,K,H2O
Environments:

Metamorphic environments
Hydrothermal environments

Localities

At the type locality, the Candoglia marble quarries, Candoglia, Mergozzo, Verbano-Cusio-Ossola Province, Piedmont, Italy, paracelsian occurs as pale yellow granules in schist (Dana).
At the Benallt Mine, Rhiw, Aberdaron, Gwynedd, Wales, UK, paracelsian is found as a hydrothermal mineral in celsian in a band in shale and sandstone associated with a metamorphosed manganese deposit. Paracelsian from this locality forms translucent white to milky-white prismatic crystals, with a vitreous lustre and chisel-shaped terminations. Specimens typically consist of an aggregate of prismatic crystals, up to 5 cm long and 1 cm wide, on less well-formed crystalline material. One specimen in the National Museum of Wales Collection shows a pale pink fluorescence. (MW).
Paracelsian from the Benallt Mine - Image

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