Bavenite

Ca4 Be2 Al2 Si9 O26 (OH)2c 2001 Mineral Data Publishing, version 1.2°

Crystal Data: Orthorhombic. Point Group: mm2: As radiating crystal groups, to 6 cm; asbladed crystals and rosettes of thin plates; also ¯ne feltlike masses of needles, compact ¯brous,chalklike massive. Twinning: On f100g.
Physical Properties:
Cleavage: Perfect on f001g, fair on f100g. Hardness = 5.5{6D(meas.) = 2.71{2.74 D(calc.) = 2.69{2.79 Weakly piezoelectric.
Optical Properties: Translucent to transparent. Color: Colorless to white. Luster: Vitreous.
Optical Class: Biaxial (+). Orientation: X = c; Y = b; Z = a.
® = 1.578{1.586¯ = 1.579{1.585 ° = 1.583{1.593 2V(meas.) = 22± {58±Cell Data:

Space Group: Am2a: a = 19.39(2)b = 23.19(2)c = 5.005(9)Z=4X-ray Powder Pattern: Baveno, Italy.
3.74 (100), 3.35 (90), 3.24 (80), 3.13 (70), 3.05 (70), 2.56 (60), 4.19 (50)
Chemistry:
SiO2
Al2 O3BeO
CaO
H2 O+H2 O¡

(1)
57.64
6.46
7.66
23.96
3.56
0.32(2)
57.83
10.90
5.35
23.99Total

99.60

100.001.93(1) Mesa Grande district, California, USA; corresponds to Ca4:11 Be2:95 Al1:22 Si9:22 O26 ² 1:90H2 O:(2) Ca4 Be2 Al2 Si9 O26 (OH)2 :Occurrence: As druses in miarolitic cavities in granite and associated pegmatites, formed byalteration of beryl and other beryllium-bearing minerals. Also in hydrothermal veins and skarns.
Association: Beryl, helvite, phenakite, bertrandite, quartz, epidote, stilbite, albite, orthoclase,titanite, chlorite, clinozoisite, tremolite.
Distribution: From Baveno and Val d'Ossola, Piedmont, Italy. At Strzegom (Striegau),Silesia, Poland. From the Czech Republic, at Jeclov, V·e·zn¶a, and near Drahon¶³n. At Takelund,southeast of Halden, Âstfold, Norway. In Switzerland, from the Muotta Nera, Piz Lai Blau, Val
Nalps and at Val Casaccia, Val Cristallina, GraubÄunden. In the USA, from the Himalaya mine,
Mesa Grande district, and in the Rincon district, San Diego Co., California; at the Foote mine,
Kings Mountain, Cleveland Co., North Carolina; from the Rutherford mine, Amelia, Amelia Co.,
Virginia; and elsewhere. In the Londonderry quarry, near Coolgardie, Western Australia. FromBatystau, central Kazakhstan. In Russia, as large crystals at Akoudertia, Siberia; Malyshero, UralMountains; and a number of other less-well-de¯ned localities.
Name:

For the original occurrence at Baveno, Italy.

Type Material: Municipal Museum of Natural History, Milan, Italy; Natural History Museum,Paris, France, 108.1881, 108.1882
References: (1) Artini, E. (1901) Di una nuova specie minerale trovata nel granito di Baveno.
Atti Rend. Accad. Lincei, 10, 139{145 (in Italian). (2) Fleischer, M.F. and G. Switzer (1953)
The bavenite problem. Amer. Mineral., 38, 988{993. (3) Switzer, G. and L.E. Reichen (1960)
Re-examination of pilinite and its identi¯cation with bavenite. Amer. Mineral., 45, 757{762.
(4) Berry, L.G. (1963) The composition of bavenite. Amer. Mineral., 48, 1166{1168. (5) Cannillo,E. and A. Coda (1966) The crystal structure of bavenite. Acta Cryst., 20, 301{309. (6) Loiacono,G.M., G. Kostecky, and J.S. White, Jr. (1982) Resolution of space group ambiguities in minerals.
Amer. Mineral., 67, 846{847.
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