Chemistry:Alluaudite
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Alluaudite | |
---|---|
![]() Alluaudite | |
General | |
Category | Phosphate minerals |
Formula (repeating unit) | (Na,Ca)Mn2+ (Fe3+ ,Mn2+ ,Fe2+ ,Mg) 2(PO 4) 3 |
Strunz classification | 8.AC.10 |
Dana classification | 38.2.3.6 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | C2/c |
Unit cell | a = 11.03 Å, b = 12.53 Å c = 6.4 Å; β = 97.57°; Z = 4 |
Identification | |
Color | Dirty yellow to brownish yellow, grayish green; superficially dull greenish black, brownish black, black, when altered |
Crystal habit | Platy to radiating fibrous, nodular, granular, massive |
Twinning | Polysynthetic |
Cleavage | Distinct/ good on {100} and {010}, good on {110} |
Mohs scale hardness | 5 – 5.5 |
Streak | Brownish yellow |
Diaphaneity | Translucent |
Specific gravity | 3.4 – 3.5 |
Optical properties | Biaxial (+) |
Refractive index | nα = 1.782 nβ = 1.802 nγ = 1.835 |
Birefringence | δ = 0.053 |
Pleochroism | X = pale olive-green, straw-yellow to greenish yellow; Z = pale olive-greenish to brownish yellow |
2V angle | Measured: 50° to 90°, calculated: 78° |
References | [1][2][3] |
Alluaudite is a relatively common alkaline manganese iron phosphate mineral with the chemical formula (Na,Ca)Mn2+
(Fe3+
,Mn2+
,Fe2+
,Mg)
2(PO
4)
3. It occurs as metasomatic replacement in granitic pegmatites and within phosphatic nodules in shales.[2]
It was first described in 1848 for an occurrence in Skellefteå, Västerbotten, Sweden. It was named by Alexis Damour after François Alluaud (II) (1778–1866).[1][2] The mineral structure was first described in 1955.[5]
References
- ↑ 1.0 1.1 Alluaudite on Mindat.org
- ↑ 2.0 2.1 2.2 "Alluaudite in the Handbook of Mineralogy". http://www.handbookofmineralogy.org/pdfs/alluaudite.pdf.
- ↑ Alluaudite data on Webmineral
- ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. Bibcode: 2021MinM...85..291W.
- ↑ Nowagiel, Maciej; Samsel, Mateusz J.; Pietrzak, Tomasz K. (2021-09-01). "Towards the High Phase Purity of Nanostructured Alluaudite-Type Glass-Ceramics Cathode Materials for Sodium Ion Batteries". Materials 14 (17): 4997. doi:10.3390/ma14174997. PMID 34501086. Bibcode: 2021Mate...14.4997N.
![]() | Original source: https://en.wikipedia.org/wiki/Alluaudite.
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