64 pages, full colour.

 

UKJMM No. 26 Shipping: UK (second class) £9.00 Europe (air mail) £12.00 Rest of World (surface) £12.00 Rest of World (air mail) £14.00

In this edition of the UKJMM, priority has been given to articles describing new, unusual or rare minerals from the British Isles. These articles, together with those published in the last edition of the journal and the recent Journal of the Russell Society make a significant addition to the mineralogy of the British Isles, increasing the number of species recorded by more than 1%. This is timely, as the end of 2005 is the cut off date for references to be included in a book currently being finalised by Andy Tindle. This will be the first volume to attempt a comprehensive description of the minerals of Britain and Ireland for 150 years. Publication is expected toward the end of 2006.

We have been fortunate for this edition of the journal to receive a donation from the sale of specimens in the collection of the late John Dickinson. John passed away in December 2004 and his obituary was published in UKJMM No. 25. The donation has allowed us to increase the length of this edition by eight pages, including more articles than would otherwise be possible. We are grateful to Richard Bell who proposed the idea and who has successfully found new homes for many of John’s specimens.

The Sussex Show

The Sussex Mineral and Lapidary Society holds a mineral show at the Clair Hall in Haywards Heath in early November each year. The society has encouraged displays by private collectors and museums for many years and these mark the event out as one of the best in the UK. This year the society instigated a mineral competition along the lines of those held at the major shows in the United States. Five collectors were invited to fill a display case with British fluorite specimens, to be judged by Alan Hart of the Natural History Museum. The results were spectacular.

Since the theme was fluorite, north-of-England localities featured extensively. Only one case, from Ian Jones’ collection, had a significant number of specimens from elsewhere in the British Isles. Ian produced a superb display containing fluorite from Cornish localities, Wales and northern England. There was a particularly nice colour zoned specimen from the little known Vaynor Quarry near Merthyr Tydfil and a group of purple cubes from Halkyn Mountain in north Wales. The Cornish specimens included a small group of cut stones, these are common enough from northern England, but very rarely seen from anywhere else in the British Isles.

Next to Ian’s case, Peter Briscoe produced a display themed on a single mine. Cambokeels Mine (sometimes known also as Cammock Eals), which closed in 1990, is one of Weardale’s less well known fluorite localities. Peter assembled a superb collection of fluorite in pastel shades of green, purple and blue together with specimens coated in sparkling pyrite crusts. A couple of photographs of the mine provided an interesting backdrop.

Simon Harrison produced a stunning case of specimens from classic north of England localities including exceptional pieces from Rotherhope Fell Mine, Boltsburn Mine and Heights Mine. The Rotherhope Fell material included a classic off-matrix purple fluorite group with yellow outer zones and a large group of purple cubes lightly sprinkled with pyramidal quartz. There were also several large transparent purple to somewhat brown (the colour is hard to describe) twins from Boltsburn Mine and a large elongated yellow fluorite cube on barite from Hilton Mine, which was a real jaw dropper.

Richard Belson’s case featured a large group of clear fluorite from Heights Mine next to a bed of deep green cubes from the same locality. At either end of his display there were two lovely large polished pieces of Blue John. Surprisingly, this Derbyshire classic was absent from other displays. Last, but by no means least, Roland Thomas brought a case of fine coloured fluorites from Northern England. The most notable was a superb old-time green specimen from Middlehope Mine. This locality will be further described in the next UKJMM. Ian Jones’ case was judged the best by Alan Hart, though the real winners were the showgoers who got to see five superb cases of material not normally on public display. Congratulations to the members of SMLS who organised the show and to Ian Bruce of Crystal Classics who sponsored some of the cases. And finally ... next year, the show will be on the 11th November and the theme will be barite.

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.

18 pages.

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

4 pages

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.

2 pages

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.

2 pages.

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.

12 pages.

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.

9 pages.