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.


Carl griffiths
14 September 2020, 23:49
I have also found many dark glass like stones , on the river Neath and other rivers in the area some even on other stone.
17 August 2020, 09:36
Interesting comments re Obsidian. I live in the heart of the Brecon Beacons in a glacial valley that flows down directly down the central Brecon Beacons at about 500m altitude. My son also found what looks like a chunk of Obsidian
Iron ore has been mined and processed in the Beacons for a long time. My knowledge of teh history of the iron works is limited, but I believe most of the pig iron works in the industrial age were along the southern edge by what is the Heads of the valley road Rassau, Beaufort Ebbw Vale, Clydach etc. What would a chunk of slag be doing several miles north? Could there have been small furnaces in the mountainside above me. Could this be slag from much earlier ore smelting in the pre industrial or ancient Welsh age?

Or could it just possibly be Obsidian? Yes The Brecons are old red sandstone but I have read there are pockets of igneous geology in West Wales, Mid Wales(not to far from the Beacons) and North Wales. Obsidian formed in the Ordovician age would have been when Wales was part of the northern edge of Gondwanaland part of the microcontinent of Avalonia in the southern Hemisphere. This is 450 million years ago. Eventually Avalonia breaks free and drifts north across the equator to become part of the British Isles as we know them today. I wonder whether the immense passage of time, the action of rivers that carried the silts that make up the old red sandstone and the movement of glaciers in the ice ages could have carried the occasional bit of obsidian from an igneous to a non igneous area?

My rock looks exactly like the chunks of obsidian on Google images
I guess its probably slag....but we are finding it highly entertaining to speculate that it just might be Obsidian!

It would be good to know
Jana Horak (Head of Mineralogy & Petrology) Amgueddfa Cymru – National Museum Wales Staff
7 July 2020, 18:07

Hi, Rob, Phil and Holly

I think your descriptions are totally correct and what you have found does look like obsidian. However obsidian does not occur in South Wales. Some of the volcanic rocks in Pembrokeshire would have been obsidian when they formed in the Ordovician, but they have recrystallised so no longer have the characteristics of obsidian. So the most likely interpretation is that you have silica-rich slag from metal smelting. This really does look like obsidian. Chemically it would n't have the same exact composition, but as it is glassy it shows the characteristic conchoidal fracture, which you correctly identified. If you would like to send some images I am happy to look at them.

5 July 2020, 15:46
Hi, I have found a peach colour crystal inside a rock on Tan Y Bwlch today, similar in colour to this one listed in your pictures ‘Prismatic synchysite crystal with anatase and minor xenotime. Cwmorthin Quarry, Gwynedd. Photo: D.I. Green.’ But am not convinced that is what I have. Can I send a photo to help me get identification please? Thank you. Xx
Rob Jones
4 July 2020, 21:40
Hi Philip, Alun & Holly,
I too found some Obsidian recently, on a path on the south side of fan gyhirych along the old railway line. I thought it was just a black'ish stone until I picked it up and saw where one side was chipped, leaving that unmistakable high gloss and ringed effect. I thought Obsidian was only found in highly volacanic areas? Interested now in taking a closer look around the Abercrave area - plenty of coal and limestone spoil from past mining and quarrying here!
3 July 2020, 20:32

I've found a couple crystals in my garden, but I'm unsure of what they are. One looks like a Snow Quartz and the other looks slightly like a Celestite. I'm not sure if these are native to the area. Some help would be greatly appreciated.

Kind regards
Philip C
9 May 2020, 12:02
Good afternoon. I have found a large piece of obsidian in the garden today (50 x50x 40mm). It is completely out of context to my local geology.
Are there other instances of obsidian being found in Wales?
Thank you in advance.
Alun Ponting
11 March 2020, 23:02

May I also send in a picture for identification and verification please?

Many thanks,
7 March 2020, 12:32
Is there an email address I have a picture looked at? Also is Obsidian ever found in Wales?
Marc Haynes Amgueddfa Cymru – National Museum Wales Staff
27 September 2019, 10:33

Hi Jason,

Thank you very much for your enquiry. I have sent you the relevant curator's contact details using the e-mail address you provided.

Best wishes,

Digital Team

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