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ANKANGITE (MANNARDITE) AND CELSIAN



INFORMATIONS


This extremely rare mineral, Ba5[Ti25(V,Cr)12]O74, was described until now only from the type locality in China. Very surprising was the identification of Ankangite as bundles of black fibres to 1 cm long inside quartz crystals to 10 cm in length. Ankangite is accompanied by Celsian, an other Ba-rich mineral, Ba(Al2Si2O8). Celsian rarely shows big crystals more than 1 mm, more often is in form of sugar-like tiny white crytals above the black Ankangite needles.
The first material of this nice inclusion reached the Tucson Show in 2008. And a scientific paper described it in 2009. But in 2012, the mineral Ankangite has been discredited by IMA (the International Mineralogical Association responsible for the oversee of mineral nomenclature and classification) since it corresponds to an H2O-free variety of Mannardite, a minera know since 1983 (IMA 11-F, IMA Newsletter 13, Mineralogical Magazine, June 2012, Vol. 76(3), pp. 817).
The same quartz crystals produce an other inclusion consisting of aggregates of tiny silver metallic elongated crystals described as Jamesonite intermixed with small, clear, tabular crystals of Fluorapatite and probably more minerals as alteration of Jamesonite in a white to yellow material (can be Valentinite or Cervantite). Also has been identified in this paragenesis the very rare mineral Cebaite (Ba3Ce2(CO3)5F2). This paragenesis is younger than ankangite-celsian, it grows in a higher part of quartz crystals.
The locality is Pitangui, Belo Horizonte, Minas Gerais, Brazil.