Chiavennite, CaMnBe2Si5O13(OH)2.2H2O, a new mineral from Chiavenna (Italy)

M. Bondi, W. L. Griffin, V. Mattioli, A. Mottana

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Chiavennite, named for its type locality, occurs as euhedral orange grains and as crusts coating beryl in the Alpine pegmatites crossing the Chiavenna ultramafics in the Rhaetic Alps of Italy. With ideal formula CaMnBe2Si5O13(OH)2.2H2O, chiavennite is optically biaxial and orthorhombic: P21ab, a 8.729(5), b 31.326(11), c 4.903(2) A, Z = 4, with Dcalc. 2.657 g/cm3, Dmeas. 2.64(1) g/cm3; alpha (colourless to pale yellow) 1.581(1), gamma (yellow-orange) 1.600(1). The most intense powder XRD reflections are: 15.7(100), 2.903(100), 3.28(75), 4.15(30), 3.93(30), 3.82(30), 1.944(30) A. Chiavennite appears to form in association with bavenite and other pegmatitic minerals as the result of late-phase fluid activity in pegmatites. (A.M. 68-628)-J.A.Z.

Original languageEnglish
Pages (from-to)623-627
Number of pages5
JournalAmerican Mineralogist
Volume68
Issue number5-6
Publication statusPublished - 1983
Externally publishedYes

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