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EDITORIAL
David Green
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64 pages, full colour.
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Mineralisation in the Granite Pegmatites
at Chywoon Quarry, Cornwall
David Moulding
Jeremy Hooper
Chywoon Quarry, which works the Carnmenellis Granite,
is located between Falmouth and Helston in southwest Cornwall. It has
produced some of the finest specimens of pegmatite minerals known from
the British Isles. The quarry is a locally owned operation, which was
opened in the nineteenth century to produce dressed stone. It was subsequently
abandoned, but reopened in the 1960s for aggregate. Between 1995 and 2000
a series of pegmatite pockets lined with large crystals of K-feldspar
and quartz, and containing other minerals including albite, muscovite,
fluorapatite and fluorite were encountered. A number of large and fine
specimens of blue, green and purple prismatic fluorapatite with crystals
up to 20 mm long and dark purple cubo-octahedral fluorite of a comparable
size were produced from three large cavities. A few hand specimens of
bertrandite and calcite were also found. Late stage lower temperature
minerals present in the pegmatite cavities include the zeolites stilbite
and laumontite as well as torbernite and autunite which are likely to
have formed by supergene oxidation. This is one of the most mineralogically
remarkable pegmatite discoveries ever made in Cornwall.
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Kainosite-(Y) from the Strontian Mines,
Highland Region, Scotland
David Green
David McCallum
Kainosite-(Y) occurs as a rare late-stage primary mineral at Corrantee
and Whitesmith mines, and at the Strontian Barite Mine, north of the village
of Strontian, Highland Region, Scotland. It is a minor component of the
late-stage primary assemblage and is associated with the zeolite group
minerals brewsterite and harmotome and the strontium rare earth carbonate
ancylite-(Ce). Kainosite-(Y) occurs as yellow, white to colourless radiating
aggregates of acicular, prismatic or platy crystals, which do not usually
exceed 1 mm in length. The Strontian localities together with a discovery
from the Cuillin Granite on the Isle of Skye are the first records of
kainosite-(Y) in the British Isles
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Left: A single euhedral pink bipyramid of ancylite-(Ce), 0.8 mm across from Whitesmith Mine with radiating spherulitic aggregates of lath-like kainosite-(Y) 0.3 mm across on brown crusts of chamosite.
Centre: White to yellow balls of kainosite-(Y) to 0.5 mm on brown chamosite crusts which are poorly attached to scalenohedral calcite from Whitesmith Mine.
Right: White sprays of kainosite-(Y) to 0.1 mm overgrowing scalenohedral calcite crystals which are capped and overgrown by later generation tabular crystal, from the Strontian Barite Mine.
Photos: Julie Ballard
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The First British Occurrence of Arsenogoyazite
at
Wheal Cock, St Just, Cornwall
David Green
Andy Tindle
Richard Belson
Arsenogoyazite occurs as opaque white pseudo-cubic crystals in cavities
in quartz veinstone collected from the dumps at Wheal Cock, St Just, Cornwall.
The crystals show complex chemical substitutions. They are fluoride, sulphate
and phosphate-rich and contain significant calcium and barium. This is
the first report of arsenogoyazite in the British Isles.
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Pseudocubic white arsenogoyazite crystals 0.3 mm on edge collected by Richard Belson at Wheal Cock. Photo: Julie Ballard
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Cassedanneite from
Lady Anne Hopetoun Shaft, Leadhills, Scotland
Tim Neall
The rare lead chromate-vanadate mineral cassedanneite has been identified
as minute yellow to orange-yellow rhombs on specimens collected from the
dumps surrounding Lady Anne Hopetoun Shaft at Leadhills, South Lanarkshire,
Scotland. It occurs rarely in oxidised cellular quartz matrix with mottramite.
This is the first record of the mineral in the British Isles and the third
supergene chromate to be reported from the Leadhills-Wanlockhead mining
district.

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Remarkable Supergene Mineral Suite
from New Cliffe Hill Quarry,
Stanton under Bardon, Leicestershire
Neil Hubbard
Stephen Burchmore
David Green
New Cliffe Hill Quarry near Stanton under Bardon in Leicestershire was opened
in the mid-1980s to work an altered diorite rock of late Precambrian age
for aggregate. In the early 1990s, a mineralised structure containing a
large quantity of copper and cuprite was exposed at the unconformity between
the overlying Triassic sediments and the Precambrian basement. Cavities
in the copper-cuprite matrix and in fractures in the surrounding rock contained
a remarkable suite of copper-bearing supergene minerals including azurite,
brochantite, chalcophyllite, connellite, cuprite, libethenite, malachite,
spangolite, strashimirite, torbernite, vésigniéite, volborthite
and zálesíite. Small amounts of the lead-bearing species cerussite,
pyromorphite, mottramite and vanadinite were also identified. In 2002, a
new basic copper chloride mineral, bobkingite, named for Dr Robert J. King,
a mineralogist with an extensive publication record on the English Midlands,
was described from the quarry.
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Left: Wine-red translucent cuprite crystal 1.0 mm across with unequally developed cube, octahedron and dodecahedron faces on drusy crustose malachite. Neil Hubbard collection
Centre: Fine transparent azurite, the largest double terminated crystal on the left is 1.8 mm in length on acicular green malachite.
Right: An unusual specimen showing partly filled hexagonal crystals, perhaps epimorphous after an earlier generation of vésigniéite, to 3 mm across containing residual platy vésigniéite.
Photos: David Green |

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Algodonite and Domeykite from New
Cliffe Hill Quarry,
Stanton under Bardon, Leicestershire
Rob Ixer
Andy Tindle
Rob Chapman
The main copper assemblage found at New Cliffe Hill Quarry comprises major
amounts of cuprite, copper and malachite. Other minerals are uncommon but
include trace amounts of silver, tenorite, the copper sulphides chalcocite/djurleite,
yarrowite and the rare copper-arsenic species algodonite and domeykite.
Analyses of domeykite (Cu2.99As) show it to be close to its stoichiometric
formula Cu3As but algodonite has a range of compositions from Cu5.39As to
Cu6.07As. This paper presents the first analyses of algodonite in Britain
that are close to its stoichiometric formula. A minor sulphide assemblage
from New Cliffe Hill Quarry carries chalcopyrite, bornite, chalcocite,
spionkopite, yarrowite and covelline and in many respects has a similar
petrography to the sulphide assemblage seen at Judkins Quarry where bornite
(and its alteration product idaite), chalcopyrite, minor tetrahedrite,
trace amounts of possible cobaltite and blue copper sulphides including
geerite, djurleite, digenite, spionkopite and yarrowite occur. An origin
for the copper from Permo-Triassic red beds rather than spatially associated
Precambrian igneous rocks is favoured.

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Reviews
Mountains and Orefields: metal mining landscapes in
mid and north-east Wales
by Nigel Jones, Mark Walters and Pat Frost (2004)
Rob Ixer
Agates
by Johann Zenz (2005)
Robin Field

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