(MANNARDITE) AND CELSIAN
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
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.