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]
| Florencite-(Sm) | |
|---|---|
| General | |
| Category | Phosphate mineral |
| Formula (repeating unit) | SmAl3(PO4)2(OH)6 |
| IMA symbol | Flo-Sm[1] |
| Crystal system | Trigonal |
| Crystal class | Hexagonal scalenohedral (3m) H-M symbol: (3 2/m) |
| Space group | R3m |
| Unit cell | a = 6.972, c = 16.182 [Å]; Z = 3 |
| Identification | |
| Color | Colorless, pale pink, pale yellow |
| Crystal habit | Sub-mm zones in florencite-(Ce) crystals |
| Cleavage | {0001}, distinct |
| Fracture | Uneven |
| Mohs scale hardness | 5.5-6 |
| Luster | Vitreous to greasy |
| Streak | White |
| Density | 3.6 (measured) |
| Optical properties | Uniaxal(+) |
| Refractive index | nω=1.70, nε=1.71 |
| References | [2][3][4] |
Occurrence and association
editFlorencite-(Sm) was revealed in quartz veins in the Maldynyrd Range, Subpolar Urals, Russia. It associates with xenotime-(Y).[2]
Notes on chemistry
editFlorencite-(Sm) has admixtures of neodymium, and small amounts of cerium, gadolinium, sulfur, strontium, praseodymium, calcium, lanthanum, europium, and silicon.[2]
References
edit- ^ 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.
- ^ a b c d 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
- ^ "Florencite-(Sm) - Handbook of Mineralogy" (PDF). Handbookofmineralogy.org. Retrieved 2016-03-08.
- ^ a b c "Florencite-(Sm): Florencite-(Sm) mineral information and data". Mindat.org. Retrieved 2016-03-04.
- ^ "Florencite-(Ce): Florencite-(Ce) mineral information and data". Mindat.org. Retrieved 2016-03-09.l
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