Alluaudite | |
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General | |
Category | Phosphate minerals |
Formula (repeating unit) | (Na,Ca)Mn2+(Fe3+,Mn2+,Fe2+,Mg)2(PO4)3 |
IMA symbol | Ald [1] |
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 | [2] [3] [4] |
Alluaudite is a relatively common alkaline manganese iron phosphate mineral with the chemical formula (Na,Ca)Mn2+(Fe3+,Mn2+,Fe2+,Mg)2(PO4)3. It occurs as metasomatic replacement in granitic pegmatites and within phosphatic nodules in shales. [3]
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). [2] [3] The mineral structure was first described in 1955. [5]
Spessartine is a nesosilicate, manganese aluminium garnet species, Mn2+3Al2(SiO4)3. This mineral is sometimes mistakenly referred to as spessartite.
Lithiophilite is a mineral containing the element lithium. It is lithium manganese(II) phosphate with chemical formula LiMnPO4. It occurs in pegmatites often associated with triphylite, the iron end member in a solid solution series. The mineral with intermediate composition is known as sicklerite and has the chemical formula Li(Mn,Fe)PO4). The name lithiophilite is derived from the Greek philos (φιλός) "friend", as lithiophilite is usually found with lithium.
Triphylite is a lithium iron(II) phosphate mineral with the chemical formula LiFePO4. It is a member of the triphylite group and forms a complete solid solution series with the lithium manganese(II) phosphate, lithiophilite. Triphylite crystallizes in the orthorhombic crystal system. It rarely forms prismatic crystals and is more frequently found in hypidiomorphic rock. It is bluish- to greenish-gray in color, but upon alteration becomes brown to black.
Brushite is a phosphate mineral with the chemical formula CaHPO4·2H2O. Crystals of the pure compound belong to the monoclinic space group C2/c and are colorless. It is the phosphate analogue of the arsenate pharmacolite.
Calderite is a mineral in the garnet group with the chemical formula (Mn2+, Ca)3(Fe3+, Al)2(SiO4)3.
Jacobsite is a manganese iron oxide mineral. It is in the spinel group and forms a solid solution series with magnetite. The chemical formula is (Mn,Mg)Fe2O4 or with oxidation states and substitutions: (Mn2+,Fe2+,Mg)(Fe3+,Mn3+)2O4.
Neptunite is a silicate mineral with the formula KNa2Li(Fe2+, Mn2+)2Ti2Si8O24. With increasing manganese it forms a series with mangan-neptunite. Watatsumiite is the variety with vanadium replacing the titanium in the formula.
Alabandite or alabandine, formerly known as manganese blende or bluemenbachite is a rarely occurring manganese sulfide mineral. It crystallizes in the cubic crystal system with the chemical composition Mn2+S and develops commonly massive to granular aggregates, but rarely also cubic or octahedral crystals to 1 cm.
Hureaulite is a manganese phosphate with the formula Mn2+5(PO3OH)2(PO4)2·4H2O. It was discovered in 1825 and named in 1826 for the type locality, Les Hureaux, Saint-Sylvestre, Haute-Vienne, Limousin, France. It is sometimes written as huréaulite, but the IMA does not recommend this for English language text.
Edenite or edenitic hornblende is a double chain silicate mineral of the amphibole group with the general chemical composition NaCa2Mg5(Si7Al)O22(OH)2. Edenite is named for the locality of Edenville, Orange County, New York, where it was first described.
Lipscombite (Fe2+,Mn2+)(Fe3+)2(PO4)2(OH)2 is a green gray, olive green, or black. phosphate-based mineral containing iron, manganese, and iron phosphate.
Penikisite was discovered by Alan Kulan and Gunar Penikis near Rapid Creek, Yukon Territory. The mineral is a member of the bjarebyite group along with kulanite, ideally BaFe2+2Al2(PO4)3(OH)3, and bjarebyite, ideally BaMn2+2Al2(PO4)3(OH)3. It is among several new minerals that have been discovered in the Rapid Creek and Big Fish areas of Yukon Territory. Kulanite is similar in many ways to penikisite in appearance and properties. The chemical formula for penikisite is Ba(Mg,Fe,Ca)Al2(PO4)2(OH)3. It has a hardness of about 4 and a density of 3.79 g/cm3. Penikisite is unique among the bjarebyite group in being monoclinic and has a biaxial optical class. It comes in shades of blue and green and, when rubbed on a streak plate, is pale green to white in color. Although penikisite and kulanite both range from blue to green, penikisite zones are easily distinguishable from kulanite zones in kulanite-penikisite crystals because they are lighter than the darker kulanite in color. Penikisite is a phosphate and is different from kulanite in that it is a magnesium-rich phosphate whereas kulanite is an iron-rich phosphate.
Shigaite is a mineral with formula NaAl3(Mn2+)6(SO4)2(OH)18·12H2O that typically occurs as small, hexagonal crystals or thin coatings. It is named for Shiga Prefecture, Japan, where it was discovered in 1985. The formula was significantly revised in 1996, identifying sodium as a previously unknown constituent.
Serandite is a mineral with formula Na(Mn2+,Ca)2Si3O8(OH). The mineral was discovered in Guinea in 1931 and named for J. M. Sérand. Serandite is generally red, brown, black or colorless. The correct name lacks an accent.
Bobfergusonite is a mineral with formula Na2Mn5FeAl(PO4)6. The mineral varies in color from green-brown to red-brown. It was discovered in 1986 in Manitoba, Canada, and named for Robert Bury Ferguson (1920–2015), a professor of geological sciences at the University of Manitoba. As of 2012, the mineral has only been found in Canada and Argentina.
Messelite is a mineral with formula Ca2(Fe2+,Mn2+)(PO4)2·2H2O. It was discovered in Germany and described in 1890. The mineral was subsequently discredited in 1940, reinstated and named neomesselite in 1955, and the name restored to messelite in 1959.
Falsterite is a rare phosphate mineral with the formula Ca2MgMn2+2(Fe2+0.5Fe3+0.5)4Zn4(PO4)8(OH)4(H2O)14. It is a pegmatitic mineral, related to the currently approved mineral ferraioloite.
Ferraioloite is a rare mineral with formula MgMn2+4(Fe2+0.5Al0.5)4Zn4(PO4)8(OH)4(H2O)20. It is related to the phosphate mineral falsterite. Ferraioloite was found in pegmatites of the Foote Lithium Company Mine, Cleveland County, North Carolina, US. The name honors James (Jim) A. Ferraiolo (1947–2014).
Maneckiite is a rare phosphate mineral with the formula(Na[])Ca2Fe2+2(Fe3+Mg)Mn2(PO4)6•2H2O. It was found in Michałkowa, Góry Sowie Block, Lower Silesia, Poland.
Strunzite (Mn2+Fe3+2(PO4)2(OH)2 · 6H2O) is a light yellow mineral of the strunzite group, first discovered in 1957.