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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