•Al2/3 Fe3+
4 (SO4 )6 (OH)2 20H2 O

Aluminocopiapite

c 2001-2005 Mineral Data Publishing, version 1

Crystal Data:

Triclinic. Point Group: 1.

As minute scales and efflorescences.

Physical Properties:
Tenacity: “Fragile”. Hardness = [2–3] (by analogy to copiapite groupmembers). D(meas.) = n.d. D(calc.) = 2.163 Somewhat soluble in H2 O.
Optical Properties: Semitransparent. Color: Pale lemon-yellow to deep yellow.
Optical Class: Biaxial (+). Pleochroism: Y = colorless; Z = greenish yellow. α = 1.525
β = 1.535–1.540 γ = 1.585–1.590 2V(meas.) = Moderate.
Cell Data: Space Group: P 1. a = 7.30(1)β = 102.3(2)◦ γ = 98.7(1)◦ Z = 1b = 18.80(2)c = 7.31(1)α = 91.5(2)◦X-ray Powder Pattern: Forty Mile River, Alaska, USA [magnesian aluminocopiapite].
9.2 (10), 18.1 (8), 5.58 (8), 6.17 (7), 3.58 (5), 3.50 (5), 5.32 (3)Chemistry:SO3
Al2 O3Fe2 O3
FeO
MnO
CoO
CuO

(1)
40.59
3.08
25.62
1.03
0.08

(2)
39.18
3.12
23.16
0.17
0.16
0.05

(3)
39.642.80
26.35

MgOCaO
Na2 O
K2 O
H2 O
insol.
Total

(1)
0.28
0.03
0.15
0.01
[29.13][100.00]

(2)
1.94

(3)

30.40
1.40

31.21

[99.58]100.00(1) 1-B mine, Canada; calculated from original elemental analysis, H2 O by difference; corresponds3+•to (Al0.70 Fe2+
0.18 Mg0.09 Na0.06 Mn0.01 Ca0.01 )Σ=1.05 (Fe3.95 Al0.05 )Σ=4.00 (SO4 )6.24 (OH)2.26 18.79H2 O.
(2) Forty Mile River, Alaska, USA; original total given as 99.69%, corresponds to3+•(Mg0.59 Al0.32 Fe2+
0.03 Co0.03 Cu0.01 )Σ=0.98 (Fe3.57 Al0.43 )Σ=4.00 (SO4 )6.02 (OH)2.22 19.67H2 O.
3+•(3) Al2/3 Fe4 (SO4 )6 (OH)2 20H2 O.
Mineral Group:

Copiapite group.

Occurrence: A secondary mineral typically formed by the oxidation of pyrite in shales andcoal; may be a fumarolic reaction product.
Association:

Pyrite.

Distribution: In the USA, from “Temple Rock”, [probably the Temple Mountain district,
Emery Co.,] Utah; at Island Mountain, Trinity Co., and the Champion mine, White Mountains,
Mono Co., California; in the Coeur d’Alene mine, Central City district, Gilpin Co., Colorado; fromthe Mosquito Fork of the Forty Mile River, Eagle A-3 quadrangle, Alaska. In the 1-B mine andthe Emery seam at Glace Bay, Sydney Coalfield, Cape Breton, Nova Scotia, Canada. At Cerritos
Bayos, southwest of Calama, Antofagasta, Chile. In Italy, from the Cetine mine, 20 km southwestof Siena, Tuscany, and at the Grotto de Faraglione, Port de Levante, Vulcano, Lipari Islands.
In the Dolcoath mine, Camborne, Cornwall, England. From Morl, near Halle, Saxony-Anhalt,Germany.
Name:

For its content of aluminum and relation to the copiapite group.

Type Material:

National Museum of Natural History, Washington, D.C., USA, 93834, 103544.

References: (1) Berry, L.G. (1947) Composition and optics of copiapite. Univ. Toronto
Studies, Geol. Ser., 51, 21–34 [aluminocopiapite]. (2) (1947) Amer. Mineral., 32, 483 (abs.
ref. 1). (3) Zodrow, E.L. (1980) Hydrated sulfates from Sydney Coalfield, Cape Breton Island,Nova Scotia, Canada: the copiapite group. Amer. Mineral., 65, 961–967. (4) Bayliss, P. and A.
Atencio (1985) X-ray powder diffraction data and cell parameters for copiapite-group minerals.
Can. Mineral., 23, 53–56.
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