Mineralpedia Details for Chiavennite

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Chiavennite

Named for the type locality and only Italian locality at Tanno in Chiavenna, Lombardy. Additional localities for Chiavennite include in several localities in Norway, at the Uto mines in Sweden, and in Madagascar. Chivennite occurs in vugs in syenite pegmatite and as a coating on beryl in pegmatites. Additional associated minerals include bavenite, alancime, aegirine, helvite, eudidymite, natrolite, and feldspar.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/chiavennite.pdf

Formula: CaMn²⁺(BeOH)₂Si₅O₁₃·2H₂O
Crystal System: Orthorhombic
Cleavage: Perfect, None, None
Luster: Vitreous (Glassy)
Color: yellow, orange, red orange
Streak: white
Class: Orthorhombic - Dipyramidal
Hardness: 3
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Chiavennite from Vevja quarry, Tvedalen, Larvik, Vestfold, Norway

Small piece with a thick coating of bright orange, micaceous micro crystals of Chiavennite, a rare Beryllium zeolite.

Click thumbnail images for larger view.

Chiavennite from Tuften, Tvedalen, Larvik, Vestfold, Norway

Rusty orange tufts of Chiavennite composed of very this plates. The individual crystals can be seen in the fourth photo. Chiavennite is a rather rare beryllium mineral.