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Formula: (K,Ba,Sr)2Sr2Ca2(Ca,Na)4(Si,Al)36O72.30H2O
Tectosilicate (framework silicate), zeolite group,
barium- and strontium- bearing mineral
Crystal System: Hexagonal
Specific gravity: 2.2 measured 2.19 calculated
Hardness: 5
Streak: White
Colour: Colourless to white
Environments
Localities
The Cerro Sapo dyke, Ayopaya Province, Cochabamba, Bolivia, consists of rhythmically-layered
ankerite and baryte with bands or
irregular patches of monomineralic dark blue sodalite with crystals
reaching up to 9 cm. The dyke cross-cuts nepheline syenite,
the contact between which is strongly brecciated with an intense
sodalite–ankerite stockwork and
narrow zones of fenitisation. The dyke contains a diverse suite of
minor minerals including calcite,
microcline, natrolite,
analcime, sulphides (galena,
sphalerite, pyrite and
chalcopyrite) as well as rare-earth-element –
strontium – thorium -rich
minerals including strontianite,
strontium-bearing apatite,
goyazite, mckelveyite and
bellbergite
(MM 86.282-306).
At the type locality, the Bellerberg volcano, Vordereifel, Mayen-Koblenz District, Rhineland-Palatinate, Germany,
bellbergite occurs at the contacts of calcium-rich xenoliths in leucite
tephrite. Cavities in the hybrid zone are lined with crystals of
sanidine, clinopyroxene and altered
pyrrhotite, on which bellbergite and spheres of
thomsonite-(Ca) were deposited and succeeded by tufts of
ettringite
(AM 79.570).
Other associates of bellbergite include willhendersonite,
gismondine, jasmundite,
mayenite, chlormayenite,
srebrodolskite,
calcio-olivine and portlandite
(HOM, Mindat).
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