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Rankachite

MNHN N°199.208

visu_573 infos

FROM : Clara Mine , Wolfach, Germany
SIZE : 50 x 30 x 30 mm

general description

This sample is an association of brown crystals of rankachite with white ecru barytine and hyaline quartz. The rankachite is under the shape of spherical needdles which have a maximum size of 5 mm. The crystals of quartz are terminated and smaller. The whole sample measures 50 x 30 x 30 mm.

It comes from Clara Mine in Germany (actually the only locality of rankachite). It is today kept in the storage rooms of the collections of the Muséum national d’Histoire naturelle (i.e., not yet displayed to the public).

Photography: A. Dahmane / Photo Saint-Hilaire, © MNHN.

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The Species page

Identity card

SPECIE : Rankachite

HISTORY : Named after its type-locality : Rankach

Species described in 1984 by Kurt Walenta (1927-), German mineralogist and Pete Dunn (1942-), American mineralogist

Type-locality: Mine Clara, Rankach, Baden-Wurttemberg, Germany

CHEMICAL FORMULA : Ca Fe2+ V5+4 W6+8 O36 12H2O
CRYSTAL SYSTEM : Orthorhombic
COLOR : Dark brown to yellowish brown
DIAPHANIETY : Opaque to translucent
LUSTER : Sub-adamantine to resinous
STREAK : Brown
MORPHOLOGY : Elongated crystals, needles
HARDNESS : 2,5
DENSITY : 4,55

CHEMICAL CLASS : VII - Tungstates
GROUP : Rankachite
STRUNZ CLASS BEFORE 2001 : 7/C.34-10
STRUNZ CLASS AFTER 2001 : 7.GB.25

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