Trevorite is a very rare iron-rich Spinel Group species and garnierite is a synonym of nepouite, a rare Serpentine Group species. This very rare combination piece is certainly from a most obscure locale and country - Burundi. Musongati is a nickel, cobalt, copper lateritic deposit over a flat-lying, layered intrusion of gabbro, norite, and other mafic-ultramafic rocks (MINDAT). Pale green nepouite appears to be far richer on this specimen, than the black with a green or brown tint trevorite. It's hard to distinquish the two. There are also crusts of a splendent metallic mineral. The colors are far brighter on the back edge of the piece. Probably older material, but no proof. Ex. Jacques Montandon Collection.
Attribution: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0
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