Vuagnatite

Formula: CaAlSiO₄(OH)
Nesosilicate (insular SiO₄ groups), adelite-descloizite group
Crystal System: Orthorhombic
Specific gravity: 3.42 measured, 3.41 calculated
Hardness: 6
Streak: White
Colour: Colourless, light blue, tan
Solubility: Insoluble or only slightly soluble in hot aqua regia (Dana)
Common impurities: H₂O
Environments

Pegmatites
Metamorphic environments

All occurrences of vuagnatite suggest formation under conditions of relatively low temperature and high pressure (HOM).

Localities

At Shiraki, Toba City, Mie, Japan, vuagnatite occurs as lenses in pectolite veinlets in serpentinite (Dana).

At the type locality, Bögürtlencik Tepe, Doganbaba, Yeşilova District, Burdur Province, Turkey, vuagnatite occurs in dykes of pegmatitic anorthositic gabbro, cross-cutting harzburgite-serpentinites and affected by rodingitisation. In fresh or slightly serpentinised harzburgites these dykes are composed of anorthite, orthopyroxene and clinopyroxene, and sometimes have xenoliths of olivine, chromite and pyroxene. In some dykes vuagnatite appears in thin veinlets in association with prehnite and grossular variety hydrogrossular or with prehnite, grossular variety hydrogrossular, thomsonite, zoisite and calcite. The vuagnatite has the following two main parageneses:
firstly prehnite, vuagnatite, grossular variety hydrogrossular, relict pyroxenes, tremolite and clinochlore, and
secondly, grossular variety hydrogrossular, vuagnatite, vesuvianite and clinochlore.
The margins of these rodingitised dykes are chloritised with clinochlore as the only essential component. The diameter of crystals of vuagnatite varies between 0.03 and 0.5 mm. No alteration has been observed, but inclusions of associated minerals, especially clinochlore, vesuvianite and grossular variety hydrogrossular, are very common (AM 61.825-830). Associated minerals include chantalite, prehnite, grossular variety hydrogrossular, vesuvianite, calcite and chlorite (HOM, Dana).

At Red Mountain, Red Mountain District, Mayacmas Mountains, Mendocino county, California, USA, vuagnatite occurs in veinlets in sheared gabbro, associated with grossular variety hydrogrossular, vesuvianite, chlorite, copper and chalcocite (HOM, Dana).

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