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Al2(SO4)3 · 17H2O
Colorless in crystals, ...
Vitreous, Silky
1½ - 2
From the Latin "alum" and the Greek γεννώ ("genno"), "to create".
A hydrated aluminium sulfate.

At high temperates, alunogen may dehydrate to its pentahydrate, Unnamed (Al Sulphate-Hydrate).

Classification of Alunogen

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
C : Sulfates (selenates, etc.) without additional anions, with H2O
B : With only medium-sized cations
Dana 7th ed.:

8 : A2(XO4)3·H2O

25 : Sulphates
6 : Sulphates of Al and Tl URL:
Please feel free to link to this page.

Occurrences of Alunogen

Geological Setting:
Forms by reaction of sulfates from decomposing sulfides with aluminous minerals in shales and slates; in gossan or altered wall rock of pyritic deposits in arid regions; in coal seams;
in relatively low-temperature fumaroles.

Physical Properties of Alunogen

Vitreous, Silky
Diaphaneity (Transparency):
Colorless in crystals, aggregates white, or pale yellow or red from impurities.
colorless in transmitted light.
Hardness (Mohs):
1½ - 2

Crystallography of Alunogen

Crystal System:
Class (H-M):
1 - Pinacoidal
Crystals rare, small; prismatic [001] or {010} with a hexagonal outline about [010]; very complex, with about 60 forms noted. Commonly as delicate fibrous masses or crusts; effloresences; massive, fibrous to 5mm.

On {010}.
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Alunogen

Biaxial (+)
RI values:
nα = 1.473 nβ = 1.474 nγ = 1.480
Measured: 31° to 69°, Calculated: 46°
Max Birefringence:
δ = 0.007
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:

Chemical Properties of Alunogen

Al2(SO4)3 · 17H2O
Essential elements:
All elements listed in formula:

Relationship of Alunogen to other Species

7.CB.05Dwornikite(Ni,Fe)SO4 · H2O
7.CB.05GunningiteZnSO4 · H2O
7.CB.05KieseriteMgSO4 · H2O
7.CB.05Poitevinite(Cu,Fe,Zn)SO4 · H2O
7.CB.05SzmikiteMnSO4 · H2O
7.CB.05SzomolnokiteFeSO4 · H2O
7.CB.05CobaltkieseriteCoSO4 · H2O
7.CB.07SanderiteMgSO4 · 2H2O
7.CB.10BonattiteCuSO4 · 3H2O
7.CB.15Aplowite(Co,Mn,Ni)SO4 · 4H2O
7.CB.15Boyleite(Zn,Mg)SO4 · 4H2O
7.CB.15Ilesite(Mn,Zn,Fe)SO4 · 4H2O
7.CB.15RozeniteFeSO4 · 4H2O
7.CB.15StarkeyiteMgSO4 · 4H2O
7.CB.15DrobeciteCdSO4 · 4H2O
7.CB.15CranswickiteMgSO4 · 4H2O
7.CB.20ChalcanthiteCuSO4 · 5H2O
7.CB.20JôkokuiteMnSO4 · 5H2O
7.CB.20PentahydriteMgSO4 · 5H2O
7.CB.20SiderotilFeSO4 · 5H2O
7.CB.25Bianchite(Zn,Fe)SO4 · 6H2O
7.CB.25Chvaleticeite(Mn,Mg)SO4 · 6H2O
7.CB.25FerrohexahydriteFeSO4 · 6H2O
7.CB.25HexahydriteMgSO4 · 6H2O
7.CB.25Moorhouseite(Co,Ni,Mn)SO4 · 6H2O
7.CB.25Nickelhexahydrite(Ni,Mg,Fe)SO4 · 6H2O
7.CB.30RetgersiteNiSO4 · 6H2O
7.CB.35BieberiteCoSO4 · 7H2O
7.CB.35BoothiteCuSO4 · 7H2O
7.CB.35MallarditeMnSO4 · 7H2O
7.CB.35MelanteriteFeSO4 · 7H2O
7.CB.35Zincmelanterite(Zn,Cu,Fe)SO4 · 7H2O
7.CB.35Alpersite(Mg,Cu)[SO4] · 7H2O
7.CB.40EpsomiteMgSO4 · 7H2O
7.CB.40GoslariteZnSO4 · 7H2O
7.CB.40MorenositeNiSO4 · 7H2O
7.CB.45Meta-alunogenAl2(SO4)3 · 12H2O
7.CB.50AluminocoquimbiteFeAl(SO4)3 · 9H2O
7.CB.55CoquimbiteFe2-xAlx(SO4)3 · 9H2O, x ~0.5
7.CB.55ParacoquimbiteFe2(SO4)3 · 9H2O
7.CB.55Rhomboclase(H5O2)Fe3+(SO4)2 · 2H2O
7.CB.60KorneliteFe2(SO4)3 · 7H2O
7.CB.65QuenstedtiteFe2(SO4)3 · 11H2O
7.CB.75LishizheniteZnFe2(SO4)4 · 14H2O
7.CB.75RömeriteFe2+Fe23+(SO4)4 · 14H2O
7.CB.80RansomiteCuFe2(SO4)4 · 6H2O
7.CB.85ApjohniteMn2+Al2(SO4)4 · 22H2O
7.CB.85BíliniteFe2+Fe23+(SO4)4 · 22H2O
7.CB.85Dietrichite(Zn,Fe2+,Mn2+)Al2(SO4)4 · 22H2O
7.CB.85HalotrichiteFeAl2(SO4)4 · 22H2O
7.CB.85PickeringiteMgAl2(SO4)4 · 22H2O
7.CB.90MeridianiiteMgSO4 · 11H2O
25.6.1RostiteAl(SO4)(OH) · 5H2O
25.6.2JurbaniteAl(SO4)(OH) · 5H2O
25.6.3KhademiteAl(SO4)F · 5H2O
25.6.4Meta-aluminiteAl2(SO4)(OH)4 · 5H2O
25.6.5AluminiteAl2(SO4)(OH)4 · 7H2O
25.6.6Meta-alunogenAl2(SO4)3 · 12H2O
25.6.8FelsőbányaiteAl4(SO4)(OH)10 · 4H2O
25.6.10HydrobasaluminiteAl4(SO4)(OH)10 · 12-36H2O
25.6.11ZaheriteAl12(SO4)5(OH)26 · 20H2O
25.6.12TamarugiteNaAl(SO4)2 · 6H2O
25.6.13MendoziteNaAl(SO4)2 · 11H2O
25.6.14Alum-(Na)NaAl(SO4)2 · 12H2O
25.6.16KaliniteKAl(SO4)2 · 11H2O Not confirmed
25.6.17Alum-(K)KAl(SO4)2 · 12H2O
25.6.20Tschermigite(NH4)Al(SO4)2 · 12H2O

Other Names for Alunogen

Other Information

Other Information:
Readily soluble in water. Taste alumlike, acid and sharp.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Alunogen

Reference List:
Beudant, F.S. (1824), Trailé élémentaire de Minéralogie, 8vo, Paris: 449 (as Hydrotrisulfate d'alumine).

Mill (1828) Quarterly Journal of Science, Literature, and Art, London: 25: 382 (as Davite).

Beudant, F.S. (1832), Trailé élémentaire de Minéralogie, second edition, 2 volumes: 2: 488 (as Alunogène).

Shepard C.U. (1835) Treatise on Mineralogy. First edition: vols. 2, 3: 188 (as Solfatarite).

Glocker, E.F. (1839) Handbuch der Mineralogie, 2nd. edition, Nürnberg: 689 (as Keramohalite).

Huot, J.J. (1841) Manuel de Minéralogie. 2 volumes, Paris: 2: 451 (as Saldanite).

Glocker, E.F. (1847) Generum et specierum mineralien secundum ordines naturals digestorum synopsis. Halle: 297 (as Stypterit).

Hausmann, J.F.L. (1847) Handbuch der Mineralogie 3 volumes, Göttingen. Second edition: vol. 2, in two parts: 2: 1174 (as Halotrichit).

Rammelsberg, C.F. (1875) Handbuch der Mineralchemie. second edition: 269 (as Haarsalz).

Jirkovsky (1928) cited in Neues Jahrbuch für Mineralogie, Geologie und Paleontologie, Heidelberg, Stuttgart: I: 106.

Larsen, Esper Signius & George Steiger (1928), Dehydration and optical studies of alunogen, nontronite, and griffithite: American Journal of Science, 5th. series: 15: 1-19.

Lausen (1928) American Mineralogist: 13: 208.

Hintze, Carl (1929) Handbuch der Mineralogie. Berlin and Leipzig. 6 volumes: 1 [3B]: 4404.

Petrov (1933) Trav. Inst. Pétrog. Ac. Sc. U.R.S.S., no. 3: 89.

Zavaritsky (1935) Trans. Centr. Geol. & Prosp. Inst., Leningrad, no. 35.

Tschermaks Mineralogische und Petrographische Mitteilungen: 21: 164-178.

Gordon (1942) Academy of Science of Philadelphia, Not. Nat., no. 101

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.: 537-540.

Internet Links for Alunogen

The following Alunogen specimens are currently listed for sale on

Localities for Alunogen

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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