Florencite-(Sm)
| Florencite-(Sm) | |
|---|---|
| General | |
| Category | Phosphate mineral |
| Formula (repeating unit) | SmAl3(PO4)2(OH)6 |
| 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 | [1]"Florencite-(Sm) - Handbook of Mineralogy" (PDF). Handbookofmineralogy.org. Retrieved 2016-03-08.[2] |
Florencite-(Sm) is a very rare mineral of the plumbogummite group (alunite supergroup) with simplified formula SmAl3(PO4)2(OH)6.[2] 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),[1] which is cerium-dominant member of the plumbogummite group.[3] Florencite-(Sm) is also a samarium-analogue of florencite-(La) (lanthanum-dominant) and waylandite (bismuth-dominant), both being aluminium-rich minerals.[2]
Occurrence and association
Florencite-(Sm) was revealed in quartz veins in the Maldynyrd Range, Subpolar Urals, Russia. It associates with xenotime-(Y).[1]
Notes on chemistry
Florencite-(Sm) has admixtures of neodymium, and small amounts of cerium, gadolinium, sulfur, strontium, praseodymium, calcium, lanthanum, europium, and silicon.[1]
References
- 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
- 1 2 3 "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