Article · Wikipedia archive · Last revised Jun 19, 2026

Florencite-(Sm)

Florencite-(Sm) is a very rare mineral of the plumbogummite group (alunite supergroup) with simplified formula SmAl3(PO4)2(OH)6. 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), which is cerium-dominant member of the plumbogummite group. Florencite-(Sm) is also a samarium-analogue of florencite-(La) (lanthanum-dominant) and waylandite (bismuth-dominant), both being aluminium-rich minerals.

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Florencite-(Sm)
General
CategoryPhosphate mineral
FormulaSmAl3(PO4)2(OH)6
IMA symbolFlo-Sm1
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
References234

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

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. 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. Archived from the original (PDF) on 2016-04-01. Retrieved 2016-03-08.
  4. "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