Pumpellyite-(Al) Locality: La Flèche Quarry, Bertrix, Luxembourg Province, Belgium Field of view 6 mm. Specimen and photo Leon Hupperichs. — Photo: Leon Hupperichs · CC BY-SA 3.0
Pumpellyite-(Al)
Pumpellyite is a group of closely related sorosilicate minerals: pumpellyite-(Mg): Ca2MgAl2[Si2O6OH][SiO4](OH)2(OH) pumpellyite-(Fe2+): Ca2Fe2+Al2[Si2O6OH][SiO4](OH)2(OH) pumpellyite-(Fe3+): Ca2Fe3+Al2[Si2O6OH][SiO4](OH)2O pumpellyite-(Mn2+): Ca2Mn2+Al2[Si2O6OH][SiO4](OH)2(OH) pumpellyite-(Al): Ca2AlAl2[Si2O6OH][SiO4](OH)2O Pumpellyite crystallizes in the monoclinic-prismatic crystal system. It typically occurs as blue-green to olive green fibrous to lamellar masses. It is translucent and glassy with a Mohs hardness of 5.5 and a specific gravity of 3.2.
Intro adapted from Wikipedia (CC BY-SA).
Pumpellyite-(Al) is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₂Al₃(Si₂O₇)(SiO₄)(OH,O)₂·H₂O.
It crystallizes in the monoclinic crystal system (space group A2/m). It is a member of the Pumpellyite structural group.
Key properties: Mohs hardness 5.5; specific gravity 3.41; Colorless streak; Vitreous luster; optically biaxial.
IMA symbol Pmp-Al, IMA status: approved, named in 2005.
Found in veins cutting retrograde metamorphosed sedimentary rocks.
It is found associated with Calcite, K-feldspar, chlorite.
The suffix indicates a member of the pumpellyite group with aluminum dominant in the M1 and M2 sites. Honors Raphael Pumpelly (1837-1923).