Bertrandite, Tourmaline

Specimen ID: 9QK-AVM

Bertrandite : Be4(Si2O7)(OH)2
Tourmaline : A(D3)G6(Si6O18)(BO3)3X3Z
As recorded:
Golconda Mine, Governador Valadares, Minas Gerais, Brazil
Mindat locality:
37mm x 35mm x 25mm
From a new find at the end of 2016, these specimens are arguably the finest examples of the species extant. Back in the late 1980s or early 1990s (according to various sources) there was a discovery at the Golconda Mine that produced some extraordinary Bertrandites. These specimens were quickly forgotten, and only a few of them are seen on the market coming out of old collections. Fortunately a second (but also very limited) discovery was made at the end of 2016, and a handful more of these outstanding Bertrandites showed up at Tucson. We were lucky to have first pick from a parcel that belonged to a good friend, and we were blown away by both the size and quality of these crystals. We selected the best pieces in terms of size and quality. Betrandite is a fairly rare beryllium silicate, and crystals are typically small worldwide, usually less than 1 cm. These new specimens from Golconda feature crystals measuring OVER 3 cm(!) which is world-class for the species. Not only are these monstrous crystals, but the quality is as good as it gets showing a glossy vitreous luster and a gorgeous porcelain-white hue. This particular piece features an aesethetic group of top quality, layered groups of fine quality, highly lustrous, Bertrandite, the largest is DOUBLY-TERMINATED and measures 3.3 cm To top it off, and associated dark blue-black colored "cat's eye" Tourmaline crystal is seen on the specimen, and if that wasn't enough, one end of the crystal shows a rare beautiful fibrous termination! It's a tremendous rarity to find specimens of Bertrandite like this with such large fine quality crystals, let alone with a Tourmaline crystal sitting right in the middle. The light greenish-yellow mineral appears to be Muscovite. A great miniature specimen for anybody who collects pegmatite minerals, Brazilian minerals or just top quality minerals specimens.
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