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RM3624   Demantoid, andradite variety
Ca3Fe3+2(SiO4)3
  -  9. Silicates

In this specimen, we can observe and enjoy numerous andradite crystals, of the green demantoid variety. Faceted, lustrous, and translucent. An Alpine classic. It belongs from the Didisheim collection in Switzerland.

Size: 8 x 4 x 3.7 cm.
Main crystal: 6 mm.
Found in ±1970.
Col. Arthur Didisheim (CH - Suiza) #72
170 €
RM2550   Manganoan Diopside

Diopside specimens from Castellaccio are difficult to find today. They show aggregates of radiated prismatic diopside crystals with a lavender hue due to manganese content. It is the best known species found in rodingite (a metasomatic rock) from this Italian quarry. Various analyzes have shown the presence of Co (0.5% by weight in CoO) and Mn (1.5% by weight in MnO). Associated minerals include perovskite, grossular, andradite, magnetite, titanite, apatite, pyrrhotite, and calcite (Bedognè et al., 2006). With an interesting label, from the Naïf mineral dealer (Bormio), but I have not found more information about.

Bedognè, F., Montrasio, A., Sciesa, E. (2006): I minerali della medio-alta Valtellina delle Orobie e della Val Poschiavo. Aggiornamenti sulle altre località della provincia di Sondrio. Tipografia Bettini, Sondrio, 255 pp.

Size: 7.5 x 5.1 x 4.5 cm.
Main crystal: 1.3 cm.
Found in ±1975.
Col. J. Astor, Barcelona.
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