Florencite-(Sm)
General
CategoryPhosphate mineral
Formula
(repeating unit)		SmAl3(PO4)2(OH)6
IMA symbolFlo-Sm[1]
Crystal systemTrigonal
Crystal classHexagonal scalenohedral (3m)
H-M symbol: (3 2/m)
Space groupR3m
Unit cella = 6.972, c = 16.182 [Å]; Z = 3
Identification
ColorColorless, pale pink, pale yellow
Crystal habitSub-mm zones in florencite-(Ce) crystals
Cleavage{0001}, distinct
FractureUneven
Mohs scale hardness5.5-6
LusterVitreous to greasy
StreakWhite
Density3.6 (measured)
Optical propertiesUniaxal(+)
Refractive indexnω=1.70, nε=1.71
References[2][3][4]

Florencite-(Sm) is a very rare mineral of the plumbogummite group (alunite supergroup) with simplified formula SmAl3(PO4)2(OH)6.[4] Samarium in florencite-(Sm) is substituted by other rare earth elements, mostly neodymium. It does not form separate crystals, but is found as zones in florencite-(Ce),[2] which is cerium-dominant member of the plumbogummite group.[5] Florencite-(Sm) is also a samarium-analogue of florencite-(La) (lanthanum-dominant) and waylandite (bismuth-dominant), both being aluminium-rich minerals.[4]

Occurrence and association

Florencite-(Sm) was revealed in quartz veins in the Maldynyrd Range, Subpolar Urals, Russia. It associates with xenotime-(Y).[2]

Notes on chemistry

Florencite-(Sm) has admixtures of neodymium, and small amounts of cerium, gadolinium, sulfur, strontium, praseodymium, calcium, lanthanum, europium, and silicon.[2]

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. 1 2 3 4 Repina, S.A., Popova, V.I., Churin, E.I., Belogub, E.V., and Khiller, V.V., 2014. Florencite-(Sm)—(Sm,Nd)Al3(PO4)2(OH)6: A new mineral species of the alunite-jarosite group from the Subpolar Urals. Geology of Ore Deposits 53(7), 564-574
  3. ↑ "Florencite-(Sm) - Handbook of Mineralogy" (PDF). Handbookofmineralogy.org. Retrieved 2016-03-08.
  4. 1 2 3 "Florencite-(Sm): Florencite-(Sm) mineral information and data". Mindat.org. Retrieved 2016-03-04.
  5. ↑ "Florencite-(Ce): Florencite-(Ce) mineral information and data". Mindat.org. Retrieved 2016-03-09.l
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