Amgueddfa Blog: Geology

In recognition of this Amgueddfa Cymru – National Museum Wales will be running a series of monthly blogs, each one covering a different chemical element and its significance to Wales. Look out for these throughout the year on our website.

To start off our series of blogs, for January we have silver.

Silver (chemical symbol – Ag), atomic number 47, is one of the original seven metals of alchemy and was represented by the symbol of a crescent moon. Silver is a precious metal, but it has never been as valuable as gold.

In Wales, silver has played an important role in the history of Wales, but this is often forgotten. In the northernmost part of Ceredigion (the old county of Cardiganshire) near to the village of Goginan lie a number of disused mines which were some of the richest silver producers in the history of the British Isles. The Romans almost certainly had a part to play in the discovery of the metal-rich mineral veins, but it was Queen Elizabeth I who oversaw their development as silver mines.

It is reported that the first rich discovery of silver was made at Cwmsymlog (sometimes written as Cum sum luck in historical records) mine in 1583 by Thomas Smythe, Chief Customs Officer for the Port of London. It is much more likely that it was discovered by Ulrich Frosse, a German mining engineer experienced in silver mining who visited the mine at about the same time and advised Smythe. During the reign of Elizabeth I it is estimated that 4 tons of silver was produced from the Cardiganshire mines.

King James I and King Charles I both made handsome profits from the mines (producing 7 and 100 tons of silver respectively), so much so that in 1638 Charles I decided to establish a mint nearby at Aberystwyth Castle. Its success ultimately led to its destruction by Oliver Cromwell and the Parliamentarians during the English Civil War in 1646.

Amgueddfa Cymru holds examples of the many silver coins minted at Aberystwyth. Their characteristic feature is the three feathers on both sides of the coin. The addition of a small open book at the top signifies that the silver was produced by Thomas Bushell from the Cardiganshire mines on behalf of the Company of Mines Royal.

Maps and mine plans produced to market the silver mines to investors are some of the earliest to have been made in Britain. The Library at AC-NMW holds several versions of William Waller’s maps produced for the Company of Mine Adventurers in 1693 and 1704 as well as Sir John Pettus’ Fodinae Regales published in 1670.

One of the mines, Bwlch-yr-eskir-hir [Esgair Hir], was much hyped as the Welsh Potosi and from the silver was produced a silver ewer inscribed ‘The Mines of Bwlch-yr-Eskir-hir’, c.1692. The mine was, however, a failure. The quantity of silver produced never lived up to expectations, but this was more to do with the geology than mining methods. It is perhaps better known as the site involved in a legal case against the Crown’s control over precious metals. The case, brought by the landowner Sir Carbery Pryse in 1693, ended the tyranny of the Mines Royal.

Productive silver mining continued in north Cardiganshire, firstly, under the Company of Mine Adventurers and then through the Industrial Revolution by a number of private companies. Total silver production within this part of Wales exceeded 150 tons of silver metal.

Remarkably, it took until the 1980s for geologists to identify the mineral responsible for the high concentrations of silver in the small area of Wales. It is tetrahedrite – a copper, zinc, iron, antimony sulphide mineral - within which silver can replace some of the copper, zinc and iron. At Esgair Hir mine tetrahedrite has been recorded as containing up to 18 wt. % silver. Important ore specimens used during the identification of this mineral are preserved in our geological collections at the Museum.

Naturally occurring silver metal – known as native silver – does not occur in visible concentrations in any of the Welsh mines, but the Museum holds some of the world’s finest examples in its mineral collection. The specimens, from the Kongsberg mine in Norway, are exceptional in their quality and were acquired during the 1980s as part of the R. J. King collection.

 

Hope that you have been following our Natural Science #MuseumAdvent Calendar

Our curators and scientists in the Natural Science Department at National Museum Cardiff have been choosing their favourite objects from the collections, to place behind the doors of our very own museum advent calendar. As it is Christmas Eve, all of the doors are now open and we wanted to share with you all of the wonderful 24 objects chosen, and the staff who have helped created it. 

Why not have a look back through all of the doors and find out about these amazing objects and specimens within Amgueddfa Cymru collections.

Nadolig Llawen a blwyddyn newydd dda oddi wrth @CardiffCurator
 
Merry Christmas and a happy new year from @CardiffCurator

We are busy preparing our Natural History #MuseumAdvent calendar and we couldn't resist sharing with you a sneak preview! This year the backdrop for the calendar is a snowy National Museum Cardiff. Each of our 24 natural science curators and scientists have selected one of their favourite objects from the collections to showcase each day. The advent calendar will feature on the @CardiffCurator Twitter account, so why not tune in each day and see what natural science specimen or object is behind each door. The calendar will feature plants, insects, sea worms, shells, fossils, minerals, seaweed and diatoms to name but a few. Once we have opened all of the doors, we will reveal the curators behind the favourite objects.

Lava medallions and coins in lava from Mount Vesuvius, Italy

The National Museum Wales Petrology (Rock) collection comprises 35,000 specimens, with many interesting rock samples from across Wales and the wider World. In the drawers of the Italian collection, alongside the pumice, volcanic ash and obsidian are these curious rocks.

NMW GR.206 - Lava medallion with stamp of unknown figurehead, Vesuvius, 1871. (front)

They are called lava medallions or tablets, and along with coins embedded in lava they were probably first produced in the mid-18th Century when the ‘Grand Tour’ become fasionable among the wealthy elite of Europe.  Taking in European cities like Paris, Rome, Venice, Florence and Naples, the ‘students’ would travel with a tutor on a Grand Tour to learn about languages, geography, culture, art and architecture. When passing through Naples, the volcano of Mount Vesuvius (Vesuvio) became a must see stop on the tour. Forget postcards, fridge magnets and selfies, the take home souvenir of the day was the lava medallion!

People have long been fascinated by destructive power of Mount Vesuvius, the volcano had lain dormant for centuries before the famous eruption in 79 A.D. when the Roman cities of Pompeii and Herculaneum were destroyed. Over the last two thousand years, the volcano has erupted many times. Between eruptions, Vesuvius can lie almost dormant for long periods of time before erupting violently once again. Volcanoes the world over that erupt in this explosive style after long periods of dormancy are known as Vesuvian eruption volcanoes.

To make a lava medallion, molten lava would have been retrieved (by some very brave individual with a long stick!) from a recent lava flow or lava close enough to the surface that was accessible and still hot enough to be malleable. It was then moulded, pressed with a stamp, or embedded with a coin, cooled in a bucket of water and sold to a passing grand tourist.

The French Revolution in 1789 marked then end of Grand Tours as they were known, but with the advent of the railways in the early 19th Century and the beginnings of mass tourism, these distinct souvenirs once again became popular take-home keepsakes, and they were produced in their thousands.

Over the years many of these medallions and lava coins have found their way into museum collections across the world. They often depict kings, Roman Emperors, famous scientists or events. All of the medallions and coins in the AC NMW collection date from the 19th Century, and originate from Mount Vesuvius, but examples in other collections have originated from Mount Etna, Sicily.

If you would like to know more about lava medallions, please contact Andrew Haycock via:

https://museum.wales/staff/665/Andrew-Haycock/


NMW GR.206 – Lava medallion with stamp detailing date and place of collection, Vesuvius, 1871. (back)

NMW 15.133.GR.1 - Vesuvius, 1834. ‘note with specimen 'medallion struck in lava when it was in a hot and pasty condition’ (front)

NMW 15.133.GR.1 - Vesuvius, 1834. Note with specimen 'medallion struck in lava when it was in a hot and pasty condition’.

NMW 15.277.GR.6 – Lava with embedded coin (Victor Emmanuel II), Vesuvius. (1860s?)

NMW 15.277.GR.3 – Stamped tablet with [S]ALVATOR MADONNA one side and 1844 on other. (front)

NMW 15.277.GR.3 – Stamped tablet with [S]ALVATOR MADONNA one side and 1844 on other. (back)

NMW 24.113.GR.6 – Lava with image of Galileo, Vesuvius, 1879. (front)

NMW 24.113.GR.6 – Lava with image of Galileo, Vesuvius, 1879. (back)

NMW 15.133.GR3 – Lava with embedded coin (corroded), Vesuvius.



 

 

The discovery of the Welsh dinosaur Dracoraptor showed us that dinosaurs lived in the Jurassic of south Wales 200 million years ago. However if you went back to that time you would also have seen little shrew-like mammals hiding in the undergrowth, these are the very earliest mammals.

 

The bones and teeth of these tiny, furry creatures are preserved in caves and fissures in rocks, where perhaps they were sheltering, or even hibernating during cold winters. Fossils of these minute mammals were first found in a quarry in south Wales seventy years ago. Palaeontologists have pieced together the fragile bones to reconstruct what the animals would have looked like. One early mammal has been named Morganucodon which means "Glamorgan tooth”

 

New research undertaken at Bristol University, funded by the Natural Environmental Research Council, used powerful X-rays to scan these tiny bones making it possible to piece together the fragments digitally. Then, using modern mammals as a guide, palaeontologists digitally recreated muscles on scanned images of the skeleton. Bristol scientists used computer simulations to work out how a skeleton worked. By looking at their teeth they could tell that some early mammals were able to crunch insects with hard wing cases, while others could only bite softer ones.

 

We have a new display in our Insight gallery highlighting this research which includes an amazing model of Morganucodon, made by palaeoartist Bob Nicholls. It looks unbelievably lifelike and answers to the name Morgie!