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beadysam 2020-02-19 9:06pm

Seiber/sieber 'agate'. Anyone know anything about it?
Hi all,
I have lived at my address in Wales for about 20 years. Its a small village part way up a 'mountain' (big hill really), with no local industry that I am aware of except historical coal mining.

Anyway, about 7 years ago I got a dog, and she loves water - in the river each day. On warmer days I paddle with her and pick up any glass or other rubbish I find while she barks at rocks!!! Over the years I have found loads of pieces of blue rock in the water. The size is from a few mm up to pieces that are probably a couple of KGS. No-one local has a clue what it is and I have never been able to ID it online. I have never seen it 'out in the wild', only in the river. Its strange stuff, goes from a pale blue, through to midnight blue and even purples, sometimes there are yellowish streaks too. Sometimes it is embeded or joined with other rock or stone such as sandstone or similar. The texture of this rocks are strange too. It feels smooth and almost waxy like crayons in some places and in others it feels like glass, but with no sharp edges - and obviously, it is rough where it joins other stones.

Recently, and totally by accident I spotted some of this stuff online - I am 99% sure I am right. From what I can gather, its called Seiber or Sieber agate - although its not a rock. From what I can gather, it is slag left over from the copper industry, ovet 1400 years old, and named after the river in Germany where it was discovered. So what on earth is it doing in a stream in Wales???

I just wondered if anyone here had any experience of the stuff, and has anyone tried melting it...? My torch isn't set up at the moment, but next time I find some I will have a go at meting it. Meanwhile, anyone know anything? Thanks in advance.

Here's a couple of links to show it both in raw and polished states;

Moira 2020-02-20 12:03pm

Fascinating! Id never heard of it before.
I suppose there must have been a copper industry in your area, in the distant past. With the tin in Cornwall, Im sure it was useful in the Bronze Age!
If you fancy posting a chunk to Leicester, Im willing to see if/how it melts!


rainygrrl 2020-02-20 2:51pm

That is interesting. I’ve never heard of it before.

FosterFire 2020-02-20 3:00pm

Whoa!! Breathing that stuff can be very dangerous. Please do not try to melt it.

ESC 2020-02-20 10:05pm

This is fascinating!

beadysam 2020-02-21 1:11am


Originally Posted by FosterFire (Post 5063331)
Whoa!! Breathing that stuff can be very dangerous. Please do not try to melt it.

Oh dear, that's just what I was planning.:-k !

I have got super overkill ventilation that is on an adjustable switch. On low for general stuff but when I turn it up for powder, metal etc its like a jet engine and blows the squirrels out of the trees!!! Its an ex-hydroponics fan from a weed farm, and stank when I first got it. Its all boxed in MDF to reduce the noise, and is in the shed next door to mine, yet still sounds like its about to take off on max speed. I did all the detailed calculations when I set up and even on its lowest speed, its more than I need. So, that on max with a respirator should be fine. I am hoping someone, somewhere, has also tried melting this stuff, and how they got on.:)

Croft Eeusk 2020-02-21 7:36am

Don't know if this will be of use - but these were brought up in a simple Google search on slag.


Speedslug 2020-03-18 3:45pm

My first thought went to a flint of some kind but the copper mining idea sent that idea off to the side.

Humans do make things from various material but there are natural process that we mimic to purify the metals we play with.

I would suggest trying to 'nap off' some flakes ( with the proper PPE of course) and see how it fractures.
That might tell you a little more about it.

If you are going to take a torch to it then I recommend doing that outside on a day with a good predictable wind and PPE.

There is no telling what kind of stresses are going in a 'rock from a river' so you might even want to mount it in a vise of some sort and bring the torch up to it slowly while you hide your body behind a thick sheet of plywood or lumber.

Manufactured glass still pops and fragments with pretty good force and I would hate to hear that one of these 'rock' went boom on you and threw a chunk at you possibly damaging a vital organ.

And yeah the fumes are not going to be any more predictable either.
Arsenic and other toxic minerals could be just a sniff a way and the docs aren't going to be able guess very quickly what possible poison you inhaled any better than you are.

Now that I have satisfied my 'Nervous Nelly" habit I am as fascinated as everyone else at what you found.

Any chance you have pictures of this mysterious stone?

You could always cold work what ever it is and I found a long time ago that clear nail polish is an inexpensive way to get that wet look even if the stone itself wont polish to a high sheen.

ESC 2020-03-21 4:25pm

As far as what it's doing in the river in Wales, there are/were some famous coal mining areas in Wales. Possibly some of that was mined as far back as 1400 years ago too. (DH is part Welsh and it's part of the family lore.)

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