Monday, June 7, 2010

Menezesite, a mineral named after Brazilian mining engineer and collector Luiz Menezes

Menezesite is a mineral named in honor of Luiz Alberto Dias Menezes Filho, a Brazilian mining engineer, mineral collector and mineral dealer (born 1950 in São Paulo, Brazil), who is credited with the discovery of seven other new mineral species [1,2]. The mineral is found in the Jacupiranga mine, Cajati, São Paulo state, associated with dolomite, calcite, magnetite, clinohumite, phlogopite, ancylite-(Ce), strontianite, pyrite, and tochilinite [3].

Menezenite is composed of alkaline earth and transition metal atoms including barium, magnesium, niobium and zirconium and further contains hydrogen and oxygen atoms. It is the first-known natural heteropolyniobate [3]:
2MgZr4(BaNb12O42)·12H2O with some Ba atoms enclosed in a cage of NbO6 octahedra forming [BaNb12O42]10- anions. Menezesite has a hardness of 4 on the Mohs scale. It forms rhombododecahedral crystals with a reddish-brown to brownish-red color and a vitreous luster.

Synonym for menezesite: IMA2005-023 [2].

Keywords: mineralogy, mineral species, heteropolyniobate, heteropolyanion

References and further reading
[1] Peter Tarassoff:
Luiz Menezes (b. 1950). Rocks and Minerals March/April 2010, Volume 85, pp. 151-153.
[2] Menezesite at
[3] D. Atencio, J. M. V. Coutinho, A. C. Doriguetto, Y. P. Mascarenhas, J. Ellena and V. C. Ferrari: Menezesite, the first natural heteropolyniobate, from Cajati, São Paulo, Brazil: Description and crystal structure. American Mineralogist January 2008, Volume 93, pp. 81-87. Abstract.

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