Crystals and minerals of Wales 23 July 2009 Minerals have played a major role in the economic and social development of Wales since the Bronze Age . Since these ancient times, mineral outcrops and mines have been worked throughout Wales; by Romans and Cistercian Monks, and on into the heyday of Welsh metal mining in the mid nineteenth century, when virtually every outcropping vein or fault was tried by the drivage of adits or the sinking of shallow shafts. There are currently around 4,900 officially recognized mineral species known to occur globally, of which, 430 have been confirmed from Wales. Here we present a gallery of Welsh minerals for you to enjoy the incredible colours, forms and lustre of these magnificent museum specimens. Crystals and Minerals Colour-zoned fluorite crystal (17 x 12 mm), from Merthyr Tydfil. Fluorite is one of the earliest recorded minerals from Wales. Photo: M.P. Cooper. Inky-blue tabular anatase crystal from Tanygrisiau, Blaenau Ffestiniog. Photo: D.I. Green. Prismatic linarite crystals (largest 1.5 mm long) forming a spray. Dolwen Mine, in the Central Wales Orefield. Photo: M.P. Cooper Azurite crystal spray from Dolyhir Quarry. © D.I. Green. Freestanding crystals of azurite on drusy calcite. Dolyhir Quarry. © D.I. Green. Chalcanthite from 16 fathom level, Carreg-y-Doll Lode, Parys Mountain. Natural crystals are very rare, although crystals can easily be produced artificially. Photo: D.I. Green. Bladed wroewolfeite crystals up to 1 mm long, from Eaglebrook Mine. Langite crystals (up to 1 mm in length) from Lodge Park copper trial, near Tre'r-ddol, in the Central Wales mining district. Photo: M.P. Cooper Radial tyrolite sprays with azurite in limestone. Dolyhir Quarry. Photo: D.I. Green. Minute spherical schmiederite aggregates from Llechweddhelyg Mine, Central Wales Orefield. Field of view 3 mm wide. Photo: D.I. Green Serpierite rosettes to 5 mm from Ystrad Einion Mine, in the Central Wales Orefield. Photo: M.P. Cooper Acicular aurichalcite crystals from Machen Quarry. Tabular botallackite crystals from Neath Valley, south Wales. Photo: T.F. Cotterell. A spray (up to 0.75 mm across) of devilline crystals from near Bontddu, Gwynedd. Photo: M.P. Cooper. Pale emerald-green bladed lautenthalite microcrystals from Eaglebrook Mine. © D.I. Green. Delicate spray of redgillite crystals from Eaglebrook Mine. Photo: D.I. Green Bow-tie brochantite crystals (to 1 mm across) from Eaglebrook Mine. Photo: D.I. Green. Ramsbeckite crystals (1.5 mm), from Penrhiw Mine. Photo: D.I. Green. Redgillite sprays with brochantite from Eaglebrook Mine. Photo: D.I. Green. Bladed brochantite crystals up to 0.5 mm across, from Lodge Park copper trial, in the Central Wales Orefield. Photo: M.P. Cooper. Unknown green coating on millerite needles previously thought to be morenosite. Wyndham Deep Mine. Subsequent X-ray analysis by Amgueddfa Cymru has failed to provide confirmation. Recent research suggests that these coatings are in fact nickelhexahydrite. Photo: M.P. Cooper Lustrous, prismatic epidote crystals from Marloes Bay, Pembrokeshire. Photo: D.I. Green. Blocky enargite crystals on fluorite from Halkyn, Flintshire. Photo: T.F. Cotterell Barytocalcite from Mwyndy Mine, Llantrisant. Photo: M.P. Cooper. Yellow-brown hexagonal ewaldite crystal 2.5 mm long from Dolyhir Quarry. Ewaldite is an extremely rare mineral. © D.I. Green. Pyrite - a classic striated cubic crystal (10 x 12 mm) embedded in Cambrian slate from Penrhyn Quarry, Bethesda, Gwynedd. Cog-wheel marcasite crystals up to 10 mm across from Gwynfynydd Mine, in the Dolgellau Gold-belt. Yellow baryte crystal, Mwyndy Mine, Llantrisant. Photo: M.P. Cooper Goethite needles up to 4 mm in length from the Dolgellau Gold-belt. Photo: M.P. Cooper. Radiating goethite from Mwyndy Mine, Llantrisant, Mid Glamorgan. Photo: M.P. Cooper. Orange monazite crystal (1 mm) associated with quartz from Fron Oleu, near Prenteg, Gwynedd. Photo: M.P. Cooper Yellow, prismatic baryte crystals (up to 7 mm long) from Llwyn-saer Engine House, Mwyndy Mine. Photo M.P. Cooper Wulfenite crystals (up to 1 mm) from Elgar Mine. Photo: D.I. Green. Tabular wulfenite on hemimorphite from Bwlchrhennaid Mine. Photo: M.P. Cooper Large (5 mm on edge) tabular wulfenite crystal, Llechweddhelyg Mine, Ceredigion. A 6.5 g waterworn nugget of welsh gold, 20 mm in length. Found in 2001 following severe flash-floods on the Afon Wen, Gwynedd. Nuggets of this size are now exceptionally rare in Wales. © J.S. Mason. Partially altered synchysite rosette (2 mm across) from Gloddfa Ganol Quarry, Gwynedd. Photo: T.F. Cotterell. Glassy prismatic wavellite with spherical cacoxenite from Pwlldu beach. Photo: D.I. Green. Unusual stellate twinned siderite crystals associated with sphalerite (brown, centre right) and millerite (tarnished needles), from Wyndham Colliery. Chalcopyrite tetrahedra, Caerau Colliery. Maesteg. Crystals up to 0.5 mm cross. Chalcopyrite is the principal ore of copper. Photo: M.P. Cooper. Tabular brookite crystal from Fron Oleu, Prenteg. The crystal measures 20 mm across. Photo: M.P. Cooper Well-formed, clear, prismatic hemimorphite crystals in cavity in baryte vein. Machen Quarry. Reddish-brown bipyramidal crystals of anatase (up to 1.5 mm in size) from Hendre Quarry, Glyn Ceiriog. © M.P. Cooper. Tabular brookite (2.5 mm across) and anatase from Hendre Quarry. © M.P. Cooper. Cubic cuprite crystals, to 0.2 mm on edge, from Lodge Park copper trial, in the Central Wales Orefield. Photo: M.P. Cooper. Xanthoconite from Dolyhir Quarry. Photo: D.I. Green, © D.I. Green. Gemmy red proustite crystal (1 mm tall) from Dolyhir Quarry, Old Radnor. Proustite is one of the rarer Welsh species and highly sought-after by collectors. © D.I. Green. Erythrite encrusting quartz from the Dolgellau Gold-belt. Photo: D.I. Green Octahedral cuprite crystals (up to 0.09 mm across) from Dolyhir Quarry. © D.I. Green. Sparkling pink erythrite microcrystals from Clogau Mine. Known for many years to miners as 'cobalt bloom', erythrite is a very conspicuous mineral, due to its vivid pink colour. Photo: M.P. Cooper Colourless quartz crystal, St. David's Head. Photo: D.I. Green A cubo-octahedral siegenite crystal 1.5 mm across on siderite. Gelli Colliery, Mid Glamorgan. Photo: M.P. Cooper. Prismatic synchysite crystal with anatase and minor xenotime. Cwmorthin Quarry, Gwynedd. Photo: D.I. Green. Gemmy colourless cerussite crystals, 1-2 mm across, from Rhyd Fach Mine, in the Central Wales Orefield. Photo: M.P. Cooper. Tabular baryte crystal, South Wales coalfield. Photo: M.P. Cooper Millerite spray (25 mm in length) on siderite from the south Wales Coalfield. Millerite is justifiably one of Wales' more famous minerals, a position it shares with gold, brookite and anglesite. Photo: M.P. Cooper Cream-coloured prismatic xenotime associated with bipyramidal anatase form Blaenau Ffestiniog. Photo: D.I. Green Scanning electron micrograph of 'bow-tie' sprays of agardite-(Y). Agardite-(Y) is only known from three UK localities - one in Wales and two in Cornwall. The Welsh occurrence is at Gwaith-yr-Afon Mine in Central Wales. Backscatter-mode SEM image of a complex albite crystal with anatase (pale grey, top left) at Gloddfa Ganol Quarry, Blaenau Ffestiniog. Scanning Electron Micrograph of bipyramidal anatase crystal (0.5 mm), Cwmorthin Quarry, Blaenau Ffestiniog. Scanning electron micrograph of a small fragment of blocky arsentsumebite crystals from Dolyhir Quarry. © D.I. Green. Scanning electron micrograph of individual beudantite crystal from Dolyhir Quarry. © D.I. Green. Scanning electron micrograph of ewaldite crystal, showing stepped growth patterns from Dolyhir Quarry. Ewaldite is an extremely rare mineral previously recorded from only three other localities worldwide Scanning electron micrograph of a spray of harmotome crystals from Dolyhir Quarry. Scanning Electron Micrograph of extremely rare mattheddleite crystals. Only a few occurrences of mattheddleite known from Wales, all in microscopic quantities. Scanning electron microphotograph of a well-formed realgar crystal from Dolyhir Quarry. © D.I. Green. Scanning electron micrograph of platy synchysite-(Ce) crystals from Dolyhir Quarry in the Welsh Borderlands. Image: T.F. Cotterell. Scanning electron micrograph of sub-millimetre euhedral 'cleopatra's-needle'-shaped xenotime-(Y) crystals from Cwmorthin Quarry near Blaenau Ffestiniog, Gwynedd. Abhurite occurs exclusively on tin ingots in shipwrecks. It is formed by the chemical reaction between the tin and the chloride ions present in seawater. Here, a scanning electron micrograph shows the platy abhurite crystals discovered on tin ingots salvaged from the wreck of S.S. Liverpool off the coast of Anglesey. Scanning Electron Micrograph of a pyrite crystal. Pyrite occurres in many geological settings, including sedimentary, igneous and metamorphic rocks of all ages. Scanning electron micrograph of a pyramidal alstonite (larger crystal) with smaller, doubly-terminated paralstonite crystals, from Dolyhir Quarry.
Pottery sorting workshops Steve Burrow, 23 July 2009 Festival of British Archaeology 2009Sian, who ran yesterday's pottery sorting workshop at National Museum Cardiff, sent me a photograph of some of the joining sherds they found among the mass of material from the Llandaff Cathedral School excavations (see earlier post for background).They may not look like much, but by reconstructing these broken pots it's possible to work out what type of vessel they were once part of, what that vessel might have been used for, and sometimes when the pot was made. So, important stuff.And how did we find these joining pieces from among the many hundred sherd jigsaw puzzle that came from the excavation? We enlisted the help of dozens of sharp-eyed museum visitors who were willing to spend some time, sorting, grouping, and fitting pieces together.For visitors it was an interesting way to pass some time, for us it was an opportunity to make sense of the finds from an important site.
Andrew continues the bell making experiments Steve Burrow, 23 July 2009 Festival of British Archaeology 2009On Tuesday, Andrew Murphy, blacksmith at St Fagans continued the challenge to make a replica of an early medieval bell, begun by Tim Young earlier in the week. While Tim, had worked on brazing the body of the bell, Andrew worked on the handle. This is a loop which passes into the bell so it can be held from the top, while the bell’s clapper hangs from a hook inside.Andrew had several attempts at replicating the shape of the original bell’s handle over the course of the day, with each attempt getting closer to the form we were after, and the event was enjoyed by the public throughout the day.
Animations in a roundhouse Ian Daniel, 21 July 2009 Visitors have flocked to the Celtic Village over the last couple of days to join with us in celebrating the Festival of British Archaeology. For me so far there have been several highlights. On Sunday people found shelter from the rain in the stone roundhouse, where in the dark the artist Sean Harris projected his animation film Dadeni onto the earth beaten floor. People are used to experiencing animations on TV, computers or in a cinema. Such an experience proved moving, eerie and played upon the senses. The moving images evoked past mythologies. You almost felt as if you had gathered with the ancestors around a warm fire and cauldron to share their stories, safe from the rain. Tim Young and his team built a forge outside the Village. Their experiments in recreating the lost art of making Early Christian handbells drew the crowd. Tim felt, ‘It was a successful weekend. We were trying to understand the technique not to produce a finished product. If we were going to do this for ten day's solid we'd be getting it right completely by the end. As it is we've cracked how to do the hearth - that's great, I like it - but we need to build on it.’ Mark Rednapp, from the archaeology department here, was with them. I asked him about his thoughts, ‘The wonderful thing about experimental archaeology is that you leap from one idea to the next, one experiment to the next. Many things have passed through my mind: the skill needed to judge the temperature and timing, the amount of manual labour involved in keeping the bellows going, which remind us of early medieval slavery, but also of the apprenticeships learning from an early age by experience.’ The Festival continues until 2nd of August. Come and join my workshops ‘Colouring the past’ in the Celtic Village this weekend, the 25th and 26th of July.
Piecing together the past Chris Owen, 21 July 2009 Festival of British Archaeology 2009Today’s events at National Museum Cardiff were Shadow Puppetry and Pottery Sorting.I won’t write too much about the Shadow Puppet workshops because I covered these in a previous post – suffice it to say that they continued to be hugely popular with children, a fact demonstrated by the quantity of cut up paper and bits and bobs left behind when the crowds finally cleared.The Pottery Sorting was a new thing though. Here, visitors were helping museum staff with the real business of archaeology. Back in 2002, an excavation was carried out at Llandaff Cathedral School in Cardiff and a very large quantity of 13th and 14th-century pottery was found. This was all brought back to the museum and staff have slowly been sorting it out. But there are only so many hours in a day and this is an awful lot of pottery so, as part of last year’s National Archaeology Week, we asked the public to help us make sense of it all. The event was so popular – and we still had so much pottery left over – that we ran it again this year.So, with the help of about a hundred children and adults, Sian and Louise from the museum’s archaeology department spent today sorting the broken pottery into different types: glazed and unglazed, rims, bases and decorated pieces.It proved to be a surprisingly addictive activity, with one girl staying to help out for over an hour, and a visiting Californian potter finding herself drawn into the challenge of grouping the sherds, and trying to track down elusive joins between pieces. Sadly, no joining pieces were found but, as Sian said: “there’s always tomorrow”.And tomorrow the team will be joined by Mark Redknap, the museum’s medievalist who will be helping to make sense of it all.
