New Wales Update 01 April 2022

24 March 2022

THIS is another first for Crystal Classics, an entire Friday update of minerals from Wales.

These include many Welsh classics, some from their type localities and a fair few with unexpected fluorescent properties.  Wales is part of the United Kingdom and has a long coastline bordering the Irish Sea and the Bristol Channel to the south.  Dominated by mountainous scenery, it is a country of breath-taking landscapes, beautiful towns and villages and welcoming people.  Some of our worldwide readers may feel they know little about Wales, but if familiar with the geological time scale, three Periods emanate from Wales.  The Cambrian Period is named for the Cambrian Mountains (in Welsh, Mynyddoedd Cambria) while the Ordovician and Silurian Periods are named for two ancient British tribes, the Ordovices and Silures, who inhabited parts of Wales prior to the Roman conquest.

Although limited to our usual twenty one specimens, our selection does seem to capture the essence of Welsh mineralogy with the likes of Gwynfynydd Gold, Anglesite from its type locality on the Isle of Anglesey; Millerite from the Welsh coalfields; Anatase and Brookite from the characteristic Alpine-style mineralisation and some lovely Calcites from localities such as Parc mine and Taff’s Well.

Before looking at the specimens in a bit more detail, let’s return to the subject of Welsh gold, never a bad thing to do!  Although excellent British specimens of Native Gold are well known from Leadhills-Wanlockhead (Scotland) and Hope’s Nose (England), it is Welsh gold which is famous the world over, where it has been mined since at least the Bronze Age.  Extraction of Welsh gold was markedly increased during the Roman occupation, first from Dolaucothi near to Pumpsaint in south Wales and then from around the Dolgellau Gold Belt in the county of Gwynedd.  Two of the most famous gold mines are Gwynfynydd and Clogau, also known as Clogau St David's mine.  It is a well-known and proud fact that the gold used to make the wedding rings for many of the British royal family was mined at Clogau St David’s, including those for Queen Elizabeth II (1947); Princess Anne (1973); Diana, Princess of Wales (1981) and in more recent years Catherine, Duchess of Cambridge (2011) and Meghan, Duchess of Sussex (2018).

Following all this talk of gold, we had better begin out overview with the specimen from Gwynfynydd mine at Ganllwyd, within the Dolgellau Gold Belt.  This small cabinet specimen is largely a matrix of Clogau Shale shot through with thin Quartz stringers and crossed along one edge by a roughly 1 cm wide vein of Sphalerite.  Disseminated throughout the Sphalerite are numerous tiny Native Gold flecks and particles.  The more it is examined, the more Native Gold becomes visible!  The specimen is from the Chidlaw Lode on 6 Level, one of about 20 known gold-bearing veins.

At one time the copper mine at Parys Mountain on Anglesey was the largest produced of copper in the world.  Much of the mine was underground, but the massive open pit remains undisturbed to this day, appearing more like a Martian landscape with its vivid patchwork of orange, yellow, chocolate, ochre, cream and pink.  The original Mona mine was soon enveloped by the much larger Parys mine, but it was from the former that the lead sulphate was first recognised and named Anglesite, for Anglesey.  We have two quite different Anglesite specimens from Parys Mountain, one with several beautiful old labels and one rich in sparkling pale yellow-tan Anglesite crystals and under LWUV fluoresces bright lemon yellow.

Wales is famous for its extensive coalfields which, sadly, are no longer worked.  Coal mines don’t readily conjure the thought of superb mineral specimens, but one iconic product of the Welsh coalfields is the nickel sulphide Millerite.  Our selection includes three Millerites, all from the Coed-Ely Colliery in what is now named Rhondda Cynon Taf in south Wales.  Coed-Ely Colliery began in 1901, operated by the Welsh Navigation Steam Coal Co. Ltd. and continued production until its eventual closure in November 1986.  In all three specimens the Millerite forms as characteristic acicular golden rods, sometimes relatively thick and sometimes hair-like.  It occurs with curved bladed crystals of Siderite and often a little Quartz in a hard rusty ironstone.  In one specimen, superb Millerite crystals criss-cross a Siderite-lined cavity, obviously a good specimen as it was in Richard Barstow’s personal collection and is accompanied with one of his white labels.

The Benallt mine on the Lleyn Peninsula in Gwynedd is an amazing locality even though the mine operated for only eight years between 1886 and 1894, followed by a short period for the supply of manganese during World War II.  Many rare minerals can be found, including four for which it is the type locality.  Paracelsian, a rare barium aluminium silicate, can form magnificent specimens at Benallt and this small cabinet display piece is a splendid example.  It was collected by Sir Arthur Russell in 1911 and is accompanied with his handwritten label, naming it as “Benallt Manganese Mine”.  The specimen is composed almost entirely of Paracelsian, with crystals up to 1.5 cm long.

The selection includes a few fine Calcites with a lovely miniature from Taff’s Well quarry, close to Cardiff.  This specimen shows two generations of Calcite growth, with two light tan scalenohedral crystals coated in a secondary overgrowth of snow-white Calcite.  These crystals only reveal the underlying Calcite along their alternating narrow faces, so forming Mercedes-Benz type triangular patterns.  Under LWUV, the white secondary overgrowth fluoresces chocolate-tan, an unusual fluorescent colour, while the tan Calcite core is completely non-fluorescent, resulting in dark, non-fluorescing stripes along alternate faces.  In SWUV the Calcite fluoresces mid to bright cherry red, primarily from the first generation of tan Calcite.

Trecastell mine at Henryd, Conwy, is thought to be a very ancient mine, although the first documented records only appeared in 1753.  We have a superb large cabinet specimen whose top surface is entirely covered with large, vertically aligned, flattened Calcite rhombohedral crystals ranging between 4 and 6.5 cm wide.  All the Calcite is translucent milky white, yet typically adopts a slight pinkish hue and under LWUV fluoresces bright tangerine orange.

Other Welsh classics are Anatase and Brookite, two of the five natural forms of titanium dioxide.  Wales contains a lot of Alpine-style mineralisation and new finds are occasionally made during construction and engineering work.  A memorable example was when the new railway station was built at Tanygrisiau, a stop along the wonderful Ffestiniog line between Blaenau Ffestiniog and Porthmadog.  Excavations opened-up Alpine-type fissures filled with quartz crystals and inky blue Anatase.  Our selection includes an Anatase with Quartz, Albite and Calcite and a Brookite with Anatase, both from Prenteg in Gwynedd, the type locality for Brookite.

A quick round-up of some other specimens includes a rare crystallised Witherite from a road cutting on the A4119 at Llantrisant; a rich crystallised Cerussite from Logaulas mine at Ysbyty Ystwyth in Ceredigion; a rather unusual and aesthetic peppermint Malachite from Geufron mine in Llanidloes, Powys and beautiful crystals of turquoise Aurichalcite from Craig Rhiwarth mine, Llangynog, Powys.

Our final mention has to be a magnificent large cabinet specimen of siskin green Pyromorphite from Ceulanymaesmawr in Ceredigion.  This locality may sound more familiar as we now know it as Bwlch Glas mine.  The mine worked a lead-zinc deposit and was probably begun in the early 1800s.  A stunning 22 x 17 cm plate of crystallised milky Quartz has an approximate fifty percent coverage of Pyromorphite as micro-crystals, forming a moss-like coverage.

Wales is rightly famous for its wonderful language, dragons, daffodils, Shirley Bassey, rugby, choirs, Tom Jones and castles, to name but a few.  There is no doubt this list should also includes its minerals, of which we hope you will enjoy today’s choices and perhaps pick out one or two for yourself. 

Here is what you have to look forward to in next week's update:

Tuesday 5th April - South West England

Friday 8th April - Northern England

                                         

If you'd like to see a video of any of the specimens listed above then please contact us at orders@crystalclassics.co.uk and we'll be happy to assist you. We endeavour to respond to all enquires within 24 hours during weekdays, however at the weekend it might take us a little longer to respond.

 

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Author: JH
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