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Formula: Ca2Al3(Si2O7)(SiO4)(OH,O)2.H2O
Sorosilicate (Si2O7 groups),
pumpellyite subgroup of
the pumpellyite group
Crystal System: Monoclinic
Specific gravity: 3.41 calculated
Hardness: 5½
Streak: Colourless
Colour: Emerald-green to white, sometimes with bluish tinges
Luminescence: Not fluorescent under UV
Environments
Sedimentary environments
Metamorphic environments
Localities
At the type locality, La Flèche quarry, Bertrix, Luxembourg, Wallonia, Belgium, pumpellyite-(Al) occurs in
veins cutting retrograde metamorphosed sedimentary rocks. It forms radiating fibrous aggregates, reaching 5 mm across,
of acicular crystals. Associated minerals include calcite,
K-feldspar and chlorite.
Pumpellyite-(Al) is transparent to translucent with a vitreous lustre and one perfect cleavage
(EJM 19.2.247-253).
Pumpellyite-(Al) from La Flèche quarry -
Image
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