Pseudomalachite

Cu5 (PO4 )2 (OH)4c 2001-2005 Mineral Data Publishing, version 1

Crystal Data: Monoclinic. Point Group: 2/m. Crystals are rare, to 6 mm, typicallyrough and rounded, with prominent {110}, {201}, {311}, {100}, {001}, and others. Commonlycompact radiating and spherical, may be fibrous, in paintlike crusts and films, botryoidal, massive.
Twinning: On {100}.
Physical Properties:
Cleavage: Perfect on {100}. Fracture: Splintery. Hardness = 4.5–5
D(meas.) = 4.15–4.35 D(calc.) = 4.34
Optical Properties: Translucent. Color: Dark emerald-green, dark green, blackish green,bluish green; green to bluish green in transmitted light. Streak: Pale green to pale bluish green.
Luster: Vitreous to resinous.
Optical Class: Biaxial (–), may be biaxial (+). Pleochroism: Weak; X = bluish green to palegreen; Y = yellowish green; Z = deep bluish green to blue-green. Orientation: Z = b; X ∧ c= 21◦ –23◦ . Dispersion: r < v, strong; may be r > v. α = 1.789–1.80 β = 1.835–1.86
γ = 1.845–1.88 2V(meas.) = 46◦ –50◦
Cell Data: Space Group: P 21 /a. a = 17.02–17.08
β = 90◦ 570 −91◦ 320 Z = 2b = 5.75–5.77

c = 4.47–4.50

X-ray Powder Pattern: Ehl and Rheinbreitbach, Germany.
4.48 (10), 2.39 (8), 2.42 (6), 3.46 (5), 2.32 (5), 2.23 (5), 1.728 (5)Chemistry:P2 O5FeOCuO
H2 O

(1)
23.86
0.19
69.25
6.76

(2)
24.65
69.09
6.26

Total 100.06
100.00(1) Rheinbreitbach, Germany; corresponds to (Cu4.98 Fe0.02 )Σ=5.00 (PO4 )1.93 (OH)4.30 .
(2) Cu5 (PO4 )2 (OH)4 .
Polymorphism & Series:

Trimorphous with ludjibaite and reichenbachite.

Occurrence:

A secondary mineral in the oxidized zone of hydrothermal copper deposits.

Association:

Libethenite, malachite, cornetite, chrysocolla, quartz.

Distribution: Many localities, but usually in small amounts. In Germany, at Ehl, near Linz,
and rich specimens from Virneberg, near Rheinbreitbach, Rhineland-Palatinate. At L’ubietová,near Baňská Bystrica (Libethen, near Neusohl), Slovakia. From Nizhni Tagil and Bogoslovsk,
Ural Mountains, Russia. In England, at Caldbeck Fells, Cumbria; also from a number of mines inCornwall. From Kakanda and M’sesa, near Kambove, Katanga Province, Congo (Shaba Province,Zaire). At Mindouli, Congo Republic. From the Bwana Mkubwa, Ndola, and the Nchanga
mines, Chingola, Zambia. In the USA, from the Perkiomen and Ecton mines, Montgomery Co.,
Pennsylvania; in the Empire-Nevada mine, Yerington district, Lyon Co., Nevada; at Lone Starmine, near Safford, Graham Co., from Harquehala, La Paz Co., and elsewhere in Arizona. At
Chuquicamata, Antofagasta, Chile. Rich examples from the West Bogan mine, near Tottenham,
New South Wales, and at the Burra Burra mine, Mt. Lofty Ranges, South Australia.
Name:

From the Greek for false, as the mineral closely resembles malachite.

Type Material:

Mining Academy, Freiberg, Germany.

References: (1) Palache, C., H. Berman, and C. Frondel (1951) Dana’s system of mineralogy,(7th edition), v. II, 799–801. (2) Berry, L.G. (1950) On pseudomalachite and cornetite.
Amer. Mineral., 35, 365–385. (3) Shoemaker, G.L., J.B. Anderson, and E. Kostiner (1977)
Refinement of the crystal structure of pseudomalachite. Amer. Mineral., 62, 1042–1048.
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