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Alunite

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Chinkuahshih Mine, Jui-Fang Town, Taipei Co., Taiwan Province, Taiwan
© Rob Lavinsky

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Formula:
KAl
 
3
(SO
 
4
)
 
2
(OH)
 
6
System:TrigonalColour:white, pale shades of ...
Hardness:3½ - 4
Member of:Alunite Subgroup
Name:Named from the Latin for alum.


Alunite Subgroup.

Alunite has been used for dating (K-Ar method) of weathering processes in ore deposits or of the deposition of alunite in caves.

Classification of Alunite

IMA status:Approved
Strunz 8th edition ID:6/B.11-20
Nickel-Strunz 10th (pending) edition ID:7.BC.10

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
B : Sulfates (selenates, etc.) with additional anions, without H2O
C : With medium-sized and large cations
Dana 8th edition ID:30.2.4.1

30 : ANHYDROUS SULFATES CONTAINING HYDROXYL OR HALOGEN
2 : (AB)2(XO4)Zq
Hey's CIM Ref.:25.6.18

25 : Sulphates
6 : Sulphates of Al and Tl
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Type Occurrence of Alunite

Type Locality:Allumiere Quarries, Allumiere, Tolfa Mts District, Rome Province, Latium, Italy
Year of Discovery:1824

Occurrences of Alunite

Geological Setting:Formed between 15 C and 400 C by the action of sulfate, which may be generated from pyrite or solfataric action, on aluminous rocks, commonly accompanied by kaolinitization and silicification.

Physical Properties of Alunite

Lustre:Vitreous, Pearly
Diaphaneity (Transparency):Transparent, Translucent
Comment:Somewhat pearly on {0001}.
Colour:white, pale shades of gray, yellow, red, to reddish brown
Comment:Colorless if pure
Streak:White
Hardness (Mohs):3½ - 4
Hardness Data:Measured
Tenacity:Brittle
Cleavage:Distinct/Good
On {0001}, distinct; on {0112}, traces. Handbook of mineralogy: On {0001}, perfect
Fracture:Irregular/Uneven, Splintery, Conchoidal
Density (measured):2.6 - 2.9 g/cm3
Density (calculated):2.82 g/cm3
Comment:Values on massive material.

Crystallography of Alunite

Crystal System:Trigonal
Class (H-M):3m - Ditrigonal Pyramidal
Space Group:R3m
Cell Parameters:a = 6.98Å, c = 17.32Å
Ratio:a:c = 1 : 2.481
Unit Cell Volume:V 730.78 ų (Calculated from Unit Cell)
Morphology:Rarely in small crystals; as druses in massive material or as aggregates. Crystals tabular {0001} or terminated by flat vicinal rhombohedra; rhombohedral and commonly pseudo-cubic {0112}. Lenticular based on distortion or vicinal development. Massive, granular to dense. As rocky, admixed masses.

Crystal Atlas:
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Alunite no.1 - Goldschmidt (1913-1926)

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Optical Data of Alunite

Type:Uniaxial (+)
RI values: nω = 1.572 nε = 1.592
Maximum Birefringence:δ = 0.020

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate

Chemical Properties of Alunite

Formula:
KAl
 
3
(SO
 
4
)
 
2
(OH)
 
6
Essential elements:Al, H, K, O, S
All elements listed in formula:Al, H, K, O, S
Common Impurities:Na,Fe

Relationship of Alunite to other Species

Member of:Alunite Subgroup
Other Members of Group:

- +
Ammonioalunite
(NH
 
4
)Al
 
3
(SO
 
4
)
 
2
(OH)
 
6
Beaverite-(Zn)
Pb(Fe
3+
2
Zn)(SO
 
4
)
 
2
(OH)
 
6
Natroalunite
(Na,K)Al
 
3
(SO
 
4
)
 
2
(OH)
 
6
Common Associates:
QuartzPyriteKaoliniteHalloysiteGypsum
Diaspore
Related Minerals - Nickel-Strunz Grouping):

- +
7.BC.05D'Ansite
Na
 
21
Mg(SO
 
4
)
 
10
Cl
 
3
7.BC.10Ammonioalunite
(NH
 
4
)Al
 
3
(SO
 
4
)
 
2
(OH)
 
6
7.BC.10Ammoniojarosite
(NH
 
4
)Fe
3+
3
(SO
 
4
)
 
2
(OH)
 
6
7.BC.10Argentojarosite
AgFe
3+
3
(SO
 
4
)
 
2
(OH)
 
6
7.BC.10Beaverite-(Cu)
Pb(Fe
3+
 
,Cu)
 
3
(SO
 
4
)
 
2
(OH)
 
6
7.BC.10Dorallcharite
(Tl,K)Fe
3+
3
(SO
 
4
)
 
2
(OH)
 
6
7.BC.10Huangite
Ca
 
0.5
Al
 
3
(SO
 
4
)
 
2
(OH)
 
6
7.BC.10Hydroniumjarosite
(H
 
3
O)Fe
3+
3
(SO
 
4
)
 
2
(OH)
 
6
7.BC.10Jarosite
KFe
3+
 
 
3
(SO
 
4
)
 
2
(OH)
 
6
7.BC.10Minamiite
(Na,Ca
 
0.5
,K)Al
 
3
(SO
 
4
)
 
2
(OH)
 
6
7.BC.10Natroalunite
(Na,K)Al
 
3
(SO
 
4
)
 
2
(OH)
 
6
7.BC.10Natrojarosite
NaFe
 
3
(SO
 
4
)
 
2
(OH)
 
6
7.BC.10Osarizawaite
Pb(Al,Cu)
 
3
(SO
 
4
)
 
2
(OH)
 
6
7.BC.10Plumbojarosite
Pb
 
0.5
Fe
3+
3
(SO
 
4
)
 
2
(OH)
 
6
7.BC.10Schlossmacherite
(H
 
3
O,Ca)Al
 
3
(SO
 
4
,AsO
 
4
)
 
2
(OH)
 
6
7.BC.10Walthierite
Ba
 
0.5
Al
 
3
(SO
 
4
)
 
2
(OH)
 
6
7.BC.10Beaverite-(Zn)
Pb(Fe
3+
2
Zn)(SO
 
4
)
 
2
(OH)
 
6
7.BC.15Ye'elimite
Ca
 
4
Al
 
6
(SO
 
4
)O
 
12
7.BC.20Atlasovite
K(BiO)Cu
 
6
Fe
3+
 
(SO
 
4
)
 
5
O
 
3
Cl
7.BC.20Nabokoite
KCu
 
7
(SO
 
4
)
 
5
(Te
4+
 
O
 
3
)OCl
7.BC.25Chlorothionite
K
 
2
Cu(SO
 
4
)Cl
 
2
7.BC.30Euchlorine
KNaCu
 
3
(SO
 
4
)
 
3
O
7.BC.30Fedotovite
K
 
2
Cu
 
3
(SO
 
4
)
 
3
O
7.BC.35Kamchatkite
KCu
 
3
(SO
 
4
)
 
2
OCl
7.BC.40Piypite
K
 
2
Cu
 
2
(SO
 
4
)
 
2
O
7.BC.45Klyuchevskite
K
 
3
Cu
 
3
(Fe
3+
 
,Al)(SO
 
4
)
 
4
O
 
2
7.BC.45Alumoklyuchevskite
K
 
3
Cu
 
3
(Al,Fe
3+
 
)(SO
 
4
)
 
4
O
 
2
7.BC.50Caledonite
Pb
 
5
Cu
 
2
(SO
 
4
)
 
3
(CO
 
3
)(OH)
 
6
7.BC.55Wherryite
Pb
 
7
Cu
 
2
(SO
 
4
)
 
4
(SiO
 
4
)
 
2
(OH)
 
2
7.BC.60Mammothite
Pb
 
6
Cu
 
4
AlSb
5+
 
O
 
2
(OH)
 
16
Cl
 
4
(SO
 
4
)
 
2
7.BC.65Linarite
PbCu(SO
 
4
)(OH)
 
2
7.BC.65Schmiederite
Pb
 
2
Cu
 
2
(Se
6+
 
O
 
4
)(Se
4+
 
O
 
3
)(OH)
 
4
7.BC.65Munakataite
Pb
 
2
Cu
 
2
(Se
4+
 
O
 
3
)(SO
 
4
)(OH)
 
4
7.BC.70Chenite
Pb
 
4
Cu(SO
 
4
)
 
2
(OH)
 
6
7.BC.75Krivovichevite
Pb
 
3
Al(SO
 
4
)(OH)
 
7
7.BC.80Anhydrokainite
KMg(SO
 
4
)Cl
Related Minerals - Hey's Index Grouping:

- +
25.6.1Rostite
Al(SO
 
4
)(OH) · 5H
 
2
O
25.6.2Jurbanite
Al(SO
 
4
)(OH) · 5H
 
2
O
25.6.3Khademite
Al(SO
 
4
)F · 5H
 
2
O
25.6.4Meta-aluminite
Al
 
2
(SO
 
4
)(OH)
 
4
 · 5H
 
2
O
25.6.5Aluminite
Al
 
2
(SO
 
4
)(OH)
 
4
 · 7H
 
2
O
25.6.6Meta-alunogen
Al
 
2
(SO
 
4
)
 
3
 · 12H
 
2
O
25.6.7Alunogen
Al
 
2
(SO
 
4
)
 
3
 · 17H
 
2
O
25.6.8Felsőbányaite
Al
 
4
(SO
 
4
)(OH)
 
10
 · 4H
 
2
O
25.6.9Basaluminite
25.6.10Hydrobasaluminite
Al
 
4
(SO
 
4
)(OH)
 
10
 · 12-36H
 
2
O
25.6.11Zaherite
Al
 
12
(SO
 
4
)
 
5
(OH)
 
26
 · 20H
 
2
O
25.6.12Tamarugite
NaAl(SO
 
4
)
 
2
 · 6H
 
2
O
25.6.13Mendozite
NaAl(SO
 
4
)
 
2
 · 11H
 
2
O
25.6.14Alum-(Na)
NaAl(SO
 
4
)
 
2
 · 12H
 
2
O
25.6.15Natroalunite
(Na,K)Al
 
3
(SO
 
4
)
 
2
(OH)
 
6
25.6.16Kalinite
KAl(SO
 
4
)
 
2
 · 11H
 
2
O Not confirmed
25.6.17Alum-(K)
KAl(SO
 
4
)
 
2
 · 12H
 
2
O
25.6.19Minamiite
(Na,Ca
 
0.5
,K)Al
 
3
(SO
 
4
)
 
2
(OH)
 
6
25.6.20Tschermigite
(NH
 
4
)Al(SO
 
4
)
 
2
 · 12H
 
2
O

Other Names for Alunite

Synonyms:
AluminiliteAlumstoneCalafatiteIgnatiewiteKalioalunite
K-AluniteLœvigiteLœwigiteLowigiteNewtonite
Other Languages:
French:Alum de Rome
Pierre alumineuse de la Tolfa
German:Alaun-Grammit
Alaunspat
Alaunstein (of Werner)
Aluminilit
Alunit
Kalioalunit
K-Alunit
Lœvigit
Lœwigit
Lowigit
Latin:Alumen de Tolpha
Russian:Алунит
Simplified Chinese:明矾石
Spanish:Aluminilita
Alunita
Kalioalunita
Lœvigita
Lœwigita
Lowigita
Swedish:Romersk Alunsten

Other Information

Electrical:Strongly pyroelectric.
Other Information:Insoluble in water.
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Alunite

Reference List:

- +
Gesner C. (1565) De omni rerum fossilium genere, gemmis, lapidibus, metallis, etc. Tiguri: 13 (as Alumen de Tolpha).

Wallerius, J.G (1747) Mineralogia, eller Mineralriket. Stockholm: 163 (as Romersk Alunsten).

Delamétherie, J.C. (1797) Théorie de la Terre, 2nd. Edition, 5 volumes, Paris: 2: 113 (as Aluminilite).

Haüy, R.J. (1801) Traité de minéralogie. First edition: in 4 volumes with atlas in fol.: 2: 119 (as Alum de Rome).

Jameson, R. (1804) A System of Mineralogy. First edition, 2 volumes, Edinburgh: 1: 319 (as Alumstone).

Cordier (1820) Mém. mus. d'hist. nat.: 6: 204.

Beudant, F.S. (1824), Trailé élémentaire de Minéralogie, Paris: 449.

Mitscherlich (1861) Journal für praktische Chemie, Leipzig: 83: 474 (as Lœwigite).

Jereméjev (1883) Mineralogicheskoe Obshchestvo, Leningrad, Zapiski: 18 [2]: 221.

Flug (1887) Mineralogicheskoe Obshchestvo, Leningrad. Materialien zur Geologie Russlands. Verhandlungen: [2]: 23: 116 (as Ignatiewite).

Michel-Lévy and Lacroix (1888) Les Minéraux des Roches: 140.

Brackett and Williams (1891) American Journal of Science: 42: 11 (as Newtonite).

Calderón y Arana, S. (1910) Los minerales de España, 2 volumes, Madrid: 2: 205 (as Calafatite).

Butler and Gale (1912) USGS Bull. 511.

Schaller (1916) USGS Bull. 610: 150.

Foshag (1926) American Mineralogist: 11: 33.

Doelter, C. (1927) Handbuch der Mineral-chemie (in 4 volumes divided into parts): 4 [2]: 495-497 (as Kalioalunit).

Hintze, Carl (1929) Handbuch der Mineralogie. Berlin and Leipzig. 6 volumes: 1 [3]: 4192.

Laudermilk (1935) American Mineralogist: 20: 57.

Kagaya (1936) Journal of the Japanese Association of Mineralogy, Petrology and Economic Geology: 16: 276.

Hendricks (1937) American Mineralogist: 22: 773.

Kawano (1937) Journal of the Japanese Association of Mineralogy, Petrology and Economic Geology: 17: 31.

Willard and Proctor (1946) Economic Geology: 41: 619.

Pabst, Adolf (1947), Some computations on svanbergite, Woodhouseite and Alunite: Am. Min.: 31: 16-30.

Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged, 1124 pp.: 556-560.

Acta Crystallographica: 18: 2490-252.

Neues Jahrbuch für Mineralogie, Monatshefte (1976): 406-417.

Sato, E., Nakai, I., Miyawaki, R. & Matsubara, S. (2009): Crystal structures of alunite family minerals: beaverite, corkite, alunite, natroalunite, jarosite, svanbergite, and woodhouseite. Neues Jahrbuch für Mineralogie Abhandlungen 185, 313-322.

Internet Links for Alunite

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