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Formula: (Cu,Zn)7(SO4)2(OH)10.3H2O
Hydrated sulphate containing hydroxyl
Specific gravity: 3.28
Hardness: 2
Streak: Pale blue-green
Colour: Light blue to blue-green
Environments
Schulenbergite is a rare secondary mineral formed in the oxidised zone of
copper-zinc
bearing hydrothermal mineral deposits, commonly post-mine in
copper-zinc slags. Associated minerals include
namuwite, brochantite,
posnjakite, ktenasite,
serpierite, linarite,
malachite, cerussite,
hemimorphite, smithsonite,
gypsum, chalcopyrite,
sphalerite and quartz
(HOM).
Localities
At the Kintore open cut, New South Wales, Australia, schulenbergite has been found with serpierite
and brochantite as crystals to 0.1 mm across. The matrix is usually etched
quartz containing copper altering to
cuprite
(AJM 3.1.43).
At the type locality, the Glücksrad mine, Oberschulenberg, Clausthal-Zellerfeld, Goslar, Lower Saxony, Germany, schulenbergite is associated
with spangolite and namuwite
(AM 70.438).
At Penberthy Croft Mine, St Hilary, Mounts’s Bay District; Betterton, Cornwall, England, UK, schulenbergite occurs
as platy crystals up to about 1 mm in size on the surface of a quartz-rich
slate without any other mineral associates. Vein
quartz is present as a thin, irregular vein 1–2 mm thick on the surface of the
slate matrix about 3 mm away from the schulenbergite crystal groups.
Schulenbergite is an uncommon secondary mineral
formed by supergene oxidation processes in
copper and zinc bearing
hydrothermal polymetallic deposits, and as a post-mining alteration product of
primary chalcopyrite and
sphalerite. These sulphides may all have been consumed here during the formation of
the schulenbergite
(JRS 19.34-35).
At Silver Gill, Caldbeck Fells, Cumbria, England, UK, schulenbergite occurs as aggregates to 0.3 mm across, associated wih
ramsbeckite, posnjakite and
linarite
(JRS 8(2).85-97).
At the Smallcleugh Mine, Nenthead, Alston Moor, Eden, Cumbria, England, UK, post-mining groundwater has oxidised
primary minerals, leading to the formation of
gypsum, which in places encrusts the mine walls accompanied by various iron
oxides, epsomite and rare
serpierite. Locally these are associated with the
secondary copper
zinc basic sulphates schulenbergite and
namuwite.
At Smallcleugh schulenbergite is sparsely present as pearly, blue-green trigonal crystals which exhibit either
sharp or rounded corners, together with a perfect basal cleavage. The
serpierite is present as turquoise to copper-blue mm long bundles comprising
wispy or stellate acicular groups.
Textural evidence tentatively suggests that the schulenbergite and
namuwite at the Smallcleugh Mine formed later than the
serpierite and as the former have lower
copper:zinc ratios than
serpierite it appears that within the
supergene assemblage
copper became progressively depleted
(JRS 3.23-24).
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