Demesmaekerite

Uranium selenite mineral
(repeating unit)Pb2Cu5(UO2)2(SeO3)6(OH)6·2H2OIMA symbolDmm[1]Strunz classification4.JJ.20Dana classification34.07.06.01Crystal systemTriclinicCrystal classPinacoidal (1)
(same H-M symbol)Space groupP1Unit cella = 11.94 Å, b = 10.02 Å, c = 5.62 Å; α = 90°, β = 100°, γ = 91.91°IdentificationFormula mass2,172.01 gmColorGreen to olive green – turns brownish on dehydrationCrystal habitElongated, striated, typically in radial aggregatesCleavageNoneMohs scale hardness3–4DiaphaneityTranslucent, opaqueSpecific gravity5.28DensityMeasured 5.28(4), calculated 5.45Optical propertiesBiaxial (+)Refractive indexnα = 1.835 nγ = 1.910PleochroismVisibleDispersionStrongOther characteristics RadioactiveReferences[2][3]

Demesmaekerite is a rare uranium selenite mineral with the chemical formula: Pb2Cu5(UO2)2(SeO3)6(OH)6·2H2O.

It is named after the Belgian mineralogist Gaston Demesmaeker, who worked at the Musonoi Mine in Katanga. It is a secondary mineral which contains lead, copper and selenium, it is a bottle green to brown/yellow color, its crystal habit varies depending on where it is found. It has pleochroic attributes, which means depending on which axis it is seen, the gem displays different colors, which is an optical phenomenon. On the X axis it displays a yellow-green color, and on the Y the gem is seen in a brown color.[2] Demesmaekerite has a very strong radioactivity, 1,629,108.74, measured in GRapi (Gamma Ray American Petroleum Institute Units). It is mostly made out of oxygen (22.1%), uranium (21.92%) which causes its irradiative attributes, selenium (21.81%), lead (19.08%) which is a poisonous chemical element and copper (14.63%), but also contains hydrogen (0.46%).[4]

It can be found associated with other rare selenium-bearing uranium ores, such as haynesite, guilleminite, marthozite and piretite.[3]

References

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b Handbook of Mineralogy
  3. ^ a b Demesmaekerite mineral information and data on Mindat
  4. ^ "Demesmaekerite Mineral Data". webmineral.com. Retrieved 2021-06-22.
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Selenites, selenates, tellurites, and tellurates
Selenites 28.1
Ahlfeldite Chalcomenite Clinochalcomenite Cobaltomenite Demesmaekerite Derriksite Francisite Guilleminite Haynesite Mandarinoite Marthozite Molybdomenite Sofiite
Selenates 28.2
Olsacherite Schmiederite
Tellurites 28.3
Balyakinite Blakeite Cesbronite Chekhovichite Choloalite Cliffordite Denningite Emmonsite Eztlite Fairbankite Graemite Keystoneite Kinichilite Mackayite Moctezumite Mroseite Plumbotellurite Poughite Quetzalcoatlite Rajite Rodalquilarite Schmitterite Smirnite Sonoraite Spiroffite Teineite Winstanleyite Zemannite
Tellurates 28.4
Carlfriesite Cheremnykhite Cuzticite Dugganite Girdite Khinite Khinite-3T Kuksite Kuranakhite Montanite Oboyerite Schieffelinite Tlalocite Tlapallite Xocomecatlite Yafsoanite Yecoraite