Odd question for this forum

slowburner

I posted this in the Archaeology forum but no replies so I thought someone here might have a stab at identification - or even a guess. I probably should have included a rule in the pic for scale but the sample is 80mm x 35mm approx

Natural or man made?
This is a section through a sample of what looked to me like concrete from the bed of a small stream. In the picture it is wet - hence the black colour, when dry it is grey but the aggregate is difficult to see clearly.
From what I can gather, the aggregates in a naturally occurring conglomerate tend to be at different angles to each other and angular in their structure. In this sample, the stones are rounded and pretty much aligned in the same direction. It is softer than concrete though - could it be a 'lime-crete'?
Any thoughts very welcome indeed.

BryanF

slowburner wrote: »

I posted this in the Archaeology forum but no replies so I thought someone here might have a stab at identification - or even a guess. I probably should have included a rule in the pic for scale but the sample is 80mm x 35mm approx

lime/concrete/seashore stones(or more likely riverbed) and coal dust?

slowburner

BryanF wrote: »

lime/concrete/seashore stones(or more likely riverbed) and coal dust?

The aggregate is almost definitely from the river bed. Coal dust is an interesting thought - would that have been done in the past?
It could be just that the sample was wet when the pic was taken, when dry it looks more like concrete but still dark. You can break it at the edges between your thumbs easily enough but the centre is strong. It is much softer when wet than when dry which makes me think of a lime based mix.

heinbloed

Heat it up with a blow torch until it desintegrates. Smell and physical behavior will tell you.

slowburner

heinbloed wrote: »

Heat it up with a blow torch until it desintegrates. Smell and physical behavior will tell you.

Hang on...............

slowburner

Nope, definitely not a tar substance - no melting or anything. It didn't react at all to the blowtorch unlike concrete which shatters and spits when subjected to that kind of heat. The smell when heated was a little bit like a dirty woolen jumper.

heinbloed

If made from different substances(the coloured particels as seen in the picture) it must at least shatter. Due to different expansion coefficients.
That it did not shatter shows that the mastic (the bitumen) made up for the differing expansion rates.
Allowing the material to expand into the soft bitumen.

Heat it up UNTIL it desintegrates.

slowburner

Hang on again.........

slowburner

Some time later. I heated the heck out of the stuff and it just glowed - it wouldn't break up until I hit it with the torch head (pic 3). Pic 2 shows the different responses to heat within the samples. Must be a lot of metalliferous stuff in there - still no tarry smell.[Embedded Image Removed][Embedded Image Removed][Embedded Image Removed]

heinbloed

Must be a lot of metalliferous stuff in there

Did the colour of the torch flame change? Green for copper and chromium, yellow for iron, red for uranium, blue for cobalt, silver for titanium etc..?

How was the smell finally? Bitumen, sulfur?

Maybe worth to ask a geologist or the goelogical society.

Sometimes magma mixes with sediment, but cold magma/basalt would not show the crumbly structure seen at the edges. Hence my guessing of bitumen.

slowburner

No, the flame didn't change colour - well it stayed blue, I have heard of lots of cobalt in the groundwater around here. There was no notable smell either - just possibly a hint of sulphur, but that's all over the place here. No smell of bitumen.
Is bitumen a naturally occurring substance - interesting that you should mention magma - this area's geology is so complex because of its volcanic origins.
One thing google informed me of is that conglomerate rock tends to have the aggregate particles at different angles to each other. This stuff seems to show a rough alignment.
Are you leaning towards a verdict of natural HB? Could it be a breccia?[Embedded Image Removed]

MidlandsM

It's Kryptonite .............one of my weakness's....lol

http://en.wikipedia.org/wiki/Kryptonite

slowburner

MidlandsM wrote: »

It's Kryptonite .............one of my weakness's....lol

http://en.wikipedia.org/wiki/Kryptonite

That's just super, man.

MidlandsM

slowburner wrote: »

That's just super, man.

yes, now you have to wear your underpants outside your trousers!:D

slowburner

[Embedded Image Removed]

heinbloed

Is the picture posted at 11.17 taken before or after firing?

Are you leaning towards a verdict of natural HB? Could it be a breccia?

There are two round circular shaped enclosures, one at 12.30 and the other at 15.00 using the watch orientation. This points towards man made material.
I don't know what breccia is, man-made marble used for flooring?

Try a hydrochloric acid test (a few drops), evaporating fumes and dissolving material point towards lime content. Or after you have fired it red as you did let it cool down and spill little bit of water onto it, if the stone turns hot you have a lime stone.

Lime stone sediments can contain all sorts of particles.

If it was a left over bit from ancient furnaces/steel kilns (I have some on my lands) there would be rust visible, if heating it up or weathering it it would crumble.

slowburner

heinbloed wrote: »

Is the picture posted at 11.17 taken before or after firing?



There are two round circular shaped enclosures, one at 12.30 and the other at 15.00 using the watch orientation. This points towards man made material.
I don't know what breccia is, man-made marble used for flooring?

Try a hydrochloric acid test (a few drops), evaporating fumes and dissolving material point towards lime content. Or after you have fired it red as you did let it cool down and spill little bit of water onto it, if the stone turns hot you have a lime stone.

Lime stone sediments can contain all sorts of particles.

If it was a left over bit from ancient furnaces/steel kilns (I have some on my lands) there would be rust visible, if heating it up or weathering it it would crumble.

I stole the 11.17 pic (:o) - it's an example of a conglomerate called breccia from Google images, volcanic in origin, I think. Maybe you were thinking of terazzo.
That's a good idea about the hydrochloric acid - I'll give that a go and report back. That alone should tell me about the lime content, I think.
You wouldn't have a pic of the slag from the kilns on your lands by any chance?

heinbloed

Maybe you were thinking of terazzo.

Yes!

You wouldn't have a pic of the slag from the kilns on your lands by any chance?

No, sorry. But if you are interested in the slag you can have a bucket full or so. I found it when digging and like most stone I find it was placed on the dry stone wall along the road.
Youghal used to produce small amounts of steel before Sir Walther Ralleigh logged the oak trees (charcoal source). After that it was pottery using the furze which was left.

slowburner

heinbloed wrote: »

Yes!


No, sorry. But if you are interested in the slag you can have a bucket full or so. I found it when digging and like most stone I find it was placed on the dry stone wall along the road.
Youghal used to produce small amounts of steel before Sir Walther Ralleigh logged the oak trees (charcoal source). After that it was pottery using the furze which was left.

Not so sure I'd fancy travelling from here to Youghal for a bucket of slag:D
There's no shortage of it around here.

Anyway, I dipped the samples in Hydrochloric acid and there was zero reaction - so that rules out the presence of lime. Having looked at it under the microscope (actually the eyepiece of a set of broken binoculars) I am tending to think that it is natural. I'll send a piece off to the GSI and hope for an identification.

slowburner

It turns out the sample is natural pebbles from the bed of the stream cemented together with iron oxide.