Harmotome

Harmotome
Harmotome
General
Category	zeolites
Formula (repeating unit)	(Ba0.5,Ca0.5,Na,K)5Al5,Si11O32·12(H2O)
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/m

Harmotome is a mineral, one of the rarer zeolites; a hydrated barium silicate with formula: (Ba_0.5,Ca_0.5,Na,K)₅Al₅,Si₁₁O₃₂·12(H₂O). It forms vitreous white well defined monoclinic crystals, often associated with calcite and other zeolites. It has a Mohs hardness of 4 to 5 and a specific gravity of 2.44 to 2.5.

Named from the Greek words harmos (a joint) and temseis (I cut) because the pyramid divides parallel to the plane that passes through the terminal edges. It was first described in 1801 from an occurrence in the Harz Mountains, Lower Saxony, Germany.

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