Bavenite

bavenite

beryl

bertrandite

milarite

Images

Formula: Ca4Be2+xAl2-xSi9O26-x(OH)2+x (x= 0 to 1)
Inosilicate (chain silicate), forms a series with bohseite
Specific gravity: 2.7
Hardness: 5½
Streak: White
Colour: White
Solubility: Insoluble in common acids
Environments:

Plutonic igneous environments
Pegmatites
Metamorphic environments
Hydrothermal environments

Bavenite occurs as druses in miarolitic cavities in granite and associated pegmatites, formed by alteration of beryl and other beryllium-bearing minerals. Also in hydrothermal veins and skarn. It often forms pseudomorphs after beryl (Dana, HOM). Associated minerals include beryl, helvine, phenakite, bertrandite, quartz, epidote, stilbite, albite, orthoclase, titanite, chlorite, clinozoisite and tremolite (HOM).

Localities

At Yaogangxian mine, Yaogangxian W-Sn ore field, Yizhang county, Chenzhou, Hunan, China, a few specimens have been fond of fibrous crystals of bavenite with topaz and fluorite (Minrec 42.6.569).

At Tittling, Passau District, Lower Bavaria, Bavaria, Germany, crystals of milarite, formed from the alteration of beryl, have been found with rosettes of bavenite crystals and bavenite pseudomorphs after beryl, associated with quartz, albite and chlorite (AM 76.1836-1856, Minrec 35.5.408).

At Oberfrauenwald, Waldkirchen, Lower Bavaria, Bavaria, Germany, milarite crystals occur with quartz, bavenite and moraesite (Minrec 35.5.408).

At the Himmelleiten quarry, Roßbach, Wald, Cham, Upper Palatinate, Bavaria, Germany, milarite crystals occur in aggregates of fibrous bavenite crystals (Minrec 35.5.408).

The type locality is the Seula mine, Mount Camoscio, Oltrefiume, Baveno, Verbano-Cusio-Ossola Province, Piedmont, Italy.

At the Kalesay deposit, Ak-Tyuz ore Field, Talas Region, Kyrgyzstan, bavenite occurs with epidote (Dana).

At Malyshevo, Sverdlovsk Oblast, Russia, bavenite has been found replacing beryl variety emerald (Dana).

At the gem tourmaline mine at Mesa Grande Mining District, San Diego County, California, USA, a 7 cm pseudomorph of bavenite after beryl has been found, with residual beryl embedded in the bavenite. Considerable albite and smaller quantities of pink tourmaline, lepidolite and quartz, and black specks of manganese oxide are partially embedded in the outside of the specimen. Much of the bavenite is fibrous (AM 17.409-422).

At the Stettin pluton, Wausau Intrusive Complex, Marathon Co., Wisconsin, USA, The dike consists of thin upper and lower wall zones in contact with weathered amphibole syenite, upper and lower intermediate zones of aplite and pegmatite bands, and a coarse pegmatitic core zone. In the aplite band rare grains of bavenite have been found (R&M 94.2.184).

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