Wikipedia

Uramphite

Uramphite is a rarely-found phosphate mineral in the "phosphate, arsenate and vanadate" mineral class with chemical composition (NH4)2[UO2PO4]2·6H2O[2] from which it is seen to be a hydrated ammonium uranyl phosphate.

Uramphit
General
CategoryPhosphate, Arsenate und Vanadate
Formula
(repeating unit)
IMA symbolUap[3]
Strunz classification8.EB.15
Dana classification40.02a.07.01
Crystal systemtetragonal
Crystal classditetragonal-dipyramidal; 4/m2/m2/m[4]
Space groupP4/ncc (#130)[2]
Identification
Colorpale to bottle-green, pale yellow[5]
Cleavagestraight along two planes[6]
Mohs scale hardness2-3[5]
Lusterglass-shiny[6]
Streakgreen-white to white[5]
Diaphaneitytranslucent[6]
Density3.7 (measured), 3.26 (calculated) g/cm3[6]
Refractive indexnα = 1.564, nβ = 1.585[7]
Birefringence0.021[7]
Pleochroismcolorless vs. pale green[7]
Solubilityslightly in dilute, cold hydrochloric acid (HCl) or warm nitric acid (HNO3)

Uramphite crystallizes in the tetragonal crystal system and develops rectangular crystal faces approximately 0.2 mm wide, but is also found as rosette-like mineral aggregates and surface films. The mineral is translucent a colored light to bottle-green or light yellow with a shiny lustre on the exterior.

Etymology and history

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Uramphite was discovered in 1950[8] in the uranium-coal-bed "Tura-Kaffak" near Minkush in the Moldo Too mountains in Naryn, Kyrgyzstan. Analysis and publication followed in 1957 through the efforts of Z. A. Nekrasova (Russian: З. А. Некрасова), who named the mineral after its composition of uranium, ammonium, and phosphate.

No type location for the mineral has yet been documented.[6][9]

As uramphit was already known and acknowledged as a mineral prior to the International Mineralogical Association (IMA)'s establishment, the Commission on New Minerals, Nomenclature and Classification (CNMNC) accepted it and categorized it as a so-called "grandfathered“ (G) mineral.[1] The generally-accepted IMA/CNMNC abbreviation ("mineral symbol") for uramphite is "Uap".[3]

Classification

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Already in the old Strunz 8th edition, uramphite belongs to the "phosphate, arsenate und vanadate" mineral class, group VII/D (hydrated phosphates, arsenates and vanadates with other anions)". It belonged to the uraninite (uranium mica, VII/D.20) subgroup, forming the "uranium family" (VII/D.20a) with autunite, bassetite, fritzscheite, heinrichite, kahlerite, kirchheimerite, sodium uranospinite, nováčekite, sabugalite, saléeite, torbernite, uranocircite, uranospathite, uranospinite and zeunerite.

In Stefan Weiß's most recent (2018) edition of the Lapis Mineral Catalogue, which maintains Karl Hugo Strunz's old system for the sake of private collectors and institutions, the mineral has identifier VII/E.02-160. In the "Lapis system" this corresponds to the newly defined category of "uranyl phosphates/arsenates and uranyl vanadates with [UO2]2+–[PO4]/[AsO4]3− und [UO2]2+–[V2O8]6− and isotypic vanadates (sincosite family)". Therein uramphite forms the "meta-autunite group" with number VII/E.02 together with abernathyite, bassetite, chernikovite, lehnerite, meta-ankoleite, meta-autunite, meta-heinrichite, meta-kahlerite, meta-kirchheimerite, meta-lodèvite, meta–sodium-autunite, meta-nováčekite, meta-rauchite, meta-saléeite, meta-torbernite, meta-uranocircite, meta-uranospinite, meta-zeunerite, sodium uranospinite, ulrichite, and uramarsite.[5]

In the International Mineralogical Association (IMA)'s Strunz 9th edition (2009),[10] uramphite is listed in the "uranyl phosphates and arsenates" category. This is further grouped by atomic proportions as a uranyl complex (UO2) with phosphorus, arsenic, or vanadate complexes (RO4), so that the mineral is accordingly found in the subgroup "UO2 : RO4 = 1 : 1". There it makes up the unnamed group 8.EB.15 together with abernathyite, chernikovite, meta-ankoleite, sodium uranospinite, trögerite, and uramarsite.

Also in the Dana mineral classification system, used predominantly in the English-speaking world, uramphite is classified in the "phosphate, arsenate and vanadates" and then in the group of "hydrated phosphates etc." There it forms the unnamed subgroup 40.02a.07 together with uramarsite, found in the group "hydrated phosphates etc., with A2+(B2+)2(XO4) × x(H2O) and (UO2)2+".

Crystal structure

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Uramphite crystallizes in the tetragonal P4/ncc group (#130) with lattice parameters a = 7.02 Å and c = 18.08 Å with two formula units per unit cell.[2]

Characteristics

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The mineral is quite strongly radioactive, on account of its uranium content (up to 54.46%). Given the elemental proportions in the atomic formula and also the subsequent products in the decays series, the mineral has a specific activity of approximately 97.481 kBq/g[4] (for comparison: natural potassium has 0.0312 kBq/g). The quoted value may of course differ for any particular mineral, depending on content and retention of the decay products, as these vary the activity.

Uramphite is slightly soluble in dilute cold hydrochloric acid (HCl) and warm nitric acid (HNO3). Under UV light, uramphite shows a yellowish-green fluorescence, diminishing in intensity as the mineral is heated. If heated for a long time at 500 °C, the fluorescence vanishes entirely.[11]

Formation and discovery location

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Uramphite forms in the oxidation zone [de] of the uranium-coal bed "Tura-Kaffak" and can be found in the broken coal at a 20–50 m depth below the surface. The uramphit mineral community is generally unnamed, but in the aforementioned type locality, the (As of 2023) only known deposit,[12] gypsum and meta-autunite have been found.[13]

Safety

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Because of the mineral's strongly ionizing radiation, possible uramphite minerals should only be examined in dust- and radiation-protecting gear, and above all never stored in living-, bedding-, or workspaces. In general, absorption into the body (bodily incorporation [de], ingestion) should always be prevented and for safety direct bodily contact avoided. Handling of the mineral ought be performed wearing a mouth-guard and gloves.

See also

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Further reading

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  • З. А. Некрасова [Z. A. Nekrasova] (1957), Водный Фосфат уранила и аммония (Урамфит) – NH4(UO2)[PO4]·3H2O [A hydrous uranyl ammonium phosphate (uramphite), NH4(UO2)(PO4)·3H2O] (PDF), Voprosy Geologii Urana, Atomizdat (in Russian), pp. 67–72, retrieved 2023-06-10
  • Michael Fleischer (1959). "New mineral names" (PDF). American Mineralogist. 44: 464–470. Retrieved 2023-06-10.
  • A. N. Fitch; B. E. F. Fender (1983). "The structure of deuterated ammomium uranyl phosphate trihydrate, ND4UO2PO4·3D2O by powder neutron diffraction". Acta Crystallographica. C39 (2): 162–166. Bibcode:1983AcCrC..39..162F. doi:10.1107/S0108270183003972.
  • Igor V. Pekov (1998), Minerals first discovered on the territory of the former Soviet Union (1. ed.), Moscow: Ocean Pictures, p. 222, ISBN 5-900395-16-2
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Footnotes

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  1. ^ a b Malcolm Back; Cristian Biagioni; William D. Birch; Michel Blondieau; Hans-Peter Boja; et al. (May 2023). IMA/CNMNC, Marco Pasero (ed.). "The New IMA List of Minerals – A Work in Progress – Updated: May 2023" (PDF). cnmnc.main.jp. Archived from the original (PDF) on 2023-06-03. Retrieved 2023-06-10.
  2. ^ a b c d Hugo Strunz; Ernest H. Nickel (2001), Strunz Mineralogical Tables. Chemical-structural Mineral Classification System (9. ed.), Stuttgart: E. Schweizerbart’sche Verlagsbuchhandlung (Nägele u. Obermiller), p. 526, ISBN 3-510-65188-X
  3. ^ a b Laurence N. Warr (2021). "IMA–CNMNC approved mineral symbols" (PDF). Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. Retrieved 2023-06-10.
  4. ^ a b David Barthelmy. "Uramphite Mineral Data". webmineral.com. Retrieved 2023-06-10.
  5. ^ a b c d Stefan Weiß (2018), Das große Lapis Mineralienverzeichnis. Alle Mineralien von A – Z und ihre Eigenschaften. Stand 03/2018 (in German) (7., vollkommen neu bearbeitete und ergänzte ed.), München: Weise, ISBN 978-3-921656-83-9
  6. ^ a b c d e John W. Anthony; Richard A. Bideaux; Kenneth W. Bladh; Monte C. Nichols (2001). "Uramphite" (PDF). Handbook of Mineralogy, Mineralogical Society of America. Retrieved 2023-06-10.
  7. ^ a b c Hudson Institute of Mineralogy (ed.). "Uramphite". mindat.org. Retrieved 2023-06-10.
  8. ^ Pekov 1998
  9. ^ Commission on Museums (IMA), ed. (2021-02-12). "Catalogue of Type Mineral Specimens – U" (PDF). Retrieved 2023-06-10.
  10. ^ Ernest H. Nickel; Monte C. Nichols (Jan 2009). IMA/CNMNC (ed.). "IMA/CNMNC List of Minerals 2009" (PDF). cnmnc.main.jp. Archived from the original (PDF) on 2023-11-10. Retrieved 2023-06-10.
  11. ^ Fleischer 1959
  12. ^ Discovery location for uramphite in Mindat, accessed 10 June 2023.
  13. ^ Uramphite type locality, per Mindat, accessed 10 June 2023.
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