Pale blue aggregates of the rare Ba-Al silicate mineral cerchiaraite-(Al) from the TL in Fresno Co. California (Esquire #1 Claim, Rush Creek, Fresno County, California, United States of America). Ex. Erich Laskowski collection (USA). — Photo: David Hospital · CC BY 4.0
Cerchiaraite-(Al)
Cerchiaraite-(Al) is an IMA-recognized mineral species in the silicate class, with the chemical formula Ba₄Al₄(Si₄O₁₂)O₂(OH)₄Cl₂[Si₂O₃(OH)₄].
It crystallizes in the tetragonal crystal system (space group I4/mmm). It is a member of the Cerchiaraite structural group.
Key properties: Mohs hardness 4.5; specific gravity 3.69; Pale green-blue streak; Vitreous luster; optically uniaxial.
IMA symbol Ccr-Al, IMA status: approved, named in 2012.
Formed on the margins of quartz-sanbornite veins as a result of fluid interactions.
It is found associated with Bazirite, diopside, goethite, opal, quartz, sanbornite, titantaramellite, traskite, witherite (Esquire No. 1 claim); cerchiaraite-(Fe), pyrrhotite, muirite.
The name refers to the analog of cerchiaraite with dominant aluminum in the octahedral structural site.