Povondraite is a rare silicate mineral from the tourmaline group with formula: NaFe³⁺₃(Fe³⁺₄,Mg₂)(BO₃)₃Si₆O₁₈(OH)₃O."Povondraite"
on

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It is a dark brown to black nearly opaque mineral with a resinous to splendent luster. It crystallizes in the trigonal crystal system as equant, distorted prisms with trigonal pyramid terminations.Handbook of Mineralogy
/ref> It occurs as rare fracture and cavity encrustations within schists derived from sedimentary rocks. Associated minerals include quartz, potassium feldspar, muscovite, schorl, riebeckite and

magnesite Magnesite is a mineral with the chemical formula (magnesium carbonate). Iron, manganese, cobalt, and nickel may occur as admixtures, but only in small amounts. Occurrence Magnesite occurs as veins in and an alteration product of ultramafic ro ...

. Discovered at the San Francisco mine, near

Villa Tunari Villa Tunari or Tunari is a location in the department of Cochabamba, Bolivia. It is the seat of the Villa Tunari Municipality, the third municipal section of the Chapare Province. According to the census 2012 the population was 3,213 in the ...

(in Alto Chapare),

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, in 1976, originally it was called ferridravite, for the composition and the assumed relationship to dravite, i.e., "ferric dravite". However later investigations yielded a new empirical formula which had no relation to the dravite. This called for renaming, and the new name, after Pavel Povondra (1924–2013), a mineralogist at the Charles University in Prague, was approved by the

International Mineralogical Association Founded in 1958, the International Mineralogical Association (IMA) is an international group of 40 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 5000 plus known mineral species. Th ...

in the 1990s.Joel, D. Grice, T. Scott Encit, Frank C. Hawthorn
"Povondraite. a redefinition of the tourmaline ferridravite"
American Mineralogist, Volume 78, pages 433-436, 1993

References

{{reflist Cyclosilicates Iron(III) minerals Manganese minerals Sodium minerals Trigonal minerals Minerals in space group 160 Tourmalines