Limestone

[Janne]

I just read an article in Daily Mail that 20 limestone tools have been found in Wales.

The article says the archeologists believe the tools were used to chip designs into rocks.

But, is not limestone very soft? Suitable only for work on equally or softer rock?




http://www.dailymail.co.uk/sciencet...logists-4-500-year-old-stone-tools-Wales.html

 

[Toddy]

Depends on how much silicate is in the mix. It's a sedimentary rock and though usually composed of marine organisms, think micro shells for the most part, it does often contain iron, silicas from quartz and the like too.
Flint is usually found as nodules within limestone here.

The Daily Mail isn't renowned for good science reporting.

M

 

[John Fenna]

Depends on how much silicate is in the mix. It's a sedimentary rock and though usually composed of marine organisms, think micro shells for the most part, it does often contain iron, silicas from quartz and the like too.
Flint is usually found as nodules within limestone here.

The Daily Mail isn't renowned for good science reporting.

M

Or any accurate reporting...?

 

[Toddy]

Aye, well there is that too

M

 

[Janne]

It has been reported in other online publications too.

 

[Toddy]

Do you know how the Egytians, with only copper tools, managed to carve stone ? It's the same technique that we use to bore a hole through wood using a bow and wooden spindle.
The softer material of the 'tool' becomes embedded with fragments of sand (quartz, granite, etc.,) and it's actually the embedded hard dust that does the carving or boring.
I suspect that the limestone tools were made of the hardest stuff they could find, and that in all probability that the same embedded hard fragments, greatly enhanced their use.

M

 

[Janne]

Yes, I know. Same tech how stone slabs are cut, using soft iron wires and the recently freed stone partcles.

I had a table top made from a stone called Diabas, mined close where I lived in Sweden. Followed the manufacture closely.

I have never understood why the Egyptians did not use Bronze, as they had the metallurgical knowhow. The limestone the pyramids are mainly built from is fairly soft and easily cut, but the granite......
That is another story. That must have taken great skill and time.

 

[Robson Valley]

I bought rod and bar copper from a scrap yard. I now have copper tools. Chalcolithic.

I forged a copper knife blade from 1/4" round rod. Very pretty if all I did was cut cucumbers. Can't cut a carrot easily.
Next, I had a blacksmith forge 2 adze blades from the copper bar stock, about 1/4" thick x 1.5" wide. Won't chip wood.
And, I am very efficient at sharpening just about any edge.

I am amazed that the ancients got anything done at all with copper tool edges. In my experience, just about hopeless.
Makes me think that there was more to it, something invisible, which gave them results.

 

[Toddy]

Did you try peen hardening the edges ?

M

 

[Robson Valley]

Copper work-hardens very quickly. Even just bending thick wire like 8-guage, it becomes obvious.
I guessed that the hardening would be to my advantage in sharpening.

Forging the knife blade from the rod, I got exactly 4 whacks with a 32oz hammer and no more.
Nothing moves at all after 4. Just count then then back into the torch flame!

Actually, I made a crooked knife blade not unlike the iconic wood carving tools
common here in the Pacific Northwest native community (and others like me).

The bar stock was so big, I knew I'd never get it hot enough for long enough to get anything done.
The blacksmith (our local farrier) has a hammer striking accuracy like throwing darts. Quite a sight.
So, I took my good D adze with me so he could see a result.

Gas-fired portable horseshoe forge that can heat a shoe to yellow hot in 90 seconds.
Volcano on a tripod.

Back home, I spent ages with the sharpening process, even a little peening work with a hammer.
Just in case I had somehow softened the metal.

Fairly hopeless. Why? What did the ancients do?
I'm very pleased that I did the experiments. The tools look nice.
I hafted the big blades just like my D adze. Gave one to the farrier.

 

[Janne]

Shaping limestone by chipping away bits should be fine with copper. Smoothing limestone with other stone or copper and sludge - should be fine too.
Bu creating highly detailed granite statues with copper tools?

 

[Toddy]

Somewhere there's a video of a Zulu man chip carving ebony. His little adze is set into a thick piece of rhino hide. His chip, chip, chip, carves the surface with incredible detail, and when he's finished it needs no polishing. It's smooth and shiny and beautiful.

It's very possible to do the same with stone. Patience and skill, and time, overcomes most obstacles
People over the millennia just use what they have, to create whatever they imagine.

M

 

[Robson Valley]

Take a look at the hard stone work that the Inca and Aztec did.
Even their complex language glyphs are carved with great detain in stone.

Stone 'pecking' leaves a tell-tale surface pattern, lots of that around.

Here on the BC coast, nephrite jade blades are one of the hardest stones you can find.
Evidently, they were shaped by abrasion against other stones.

Come over to my place and sit in my shop. I'll round up stone and carvings, hard and soft,
and a box of tools and hammers, goggles. Go to it.

That is the only possible way to learn what questions to ask.

 

[Toddy]

I'm on record here as saying, time after time, that we don't do enough with stone. Very few folks handle stone, very few people make tools from stone, or use those tools. It's a fundamental 'bushcraft' material, but it's mostly ignored.
From sepentinite to flint, from sandstone to slate, from quartz to granite, it's all useful. It's all very workable.

M

 

[Robson Valley]

I'm just not set up to handle much stone dust, indoors in particular.
I like to carve in the winters and I can't afford to heat the make-up air if I used some sort of dust collection,
venting to the outdoors at -20C.

Flint knapping is one thing, pecking stone hammer heads is another. Stone cut printing.
I have flint blades that I cut up bison meat roasts with. Better than anybody's steel.
My brother has real stone hammer heads for door stops. They were bone bashers for marrow.

I guess they would not be too hard to shape even if they were roughted out with power tools.

I've begun some carved stone for printing. All the inks, papers and brayer are sitting just behind me!

Once again, it's the dust.

 

[Janne]

I would love to be able to make a stone ( flint, volcanic glass ) blade, and a Bronze one.
I think I can say the stone will never happen, but the Bronze will.


My hands are too soft to work stone. My lungs too tobacco damaged to handle the dust, and I do not want to use a respirator.

 

[Robson Valley]

When flint fractures, it breaks along a line of stone molecules. More or less, a fractured "glass."
Steel has no structure like that at all, just soft and plastic at a really thin edge.
So the flint is just deadly sharp. A long dragging cut in raw bison goes down 2-3 inches at a time.
Far less pressure needed than with a steel knife.

You can knap the bottoms of old glass soda bottles. The thick glass of old TV picture tubes.
I've seen unbelievable blades knapped from the optical glass chunks meant for optical fiber electronics.
You need a place for the dangerous off-cut flakes.

There are dozens of modern formulations for bronze. I had a crazy idea that I'd buy a "non-sparking" chisel (bronze)
find a forge and bash out a knife blade. I've too many toys already that I don't play with and the bronze tool was big $$$$.

We had an ice age melt back fairly recently in this district. Even left some local areas covered in sand dunes.
Rocks crush rocks and all the soft rocks are now sand and clay.

I suppose you could use a bar and pry pieces out of the actual mountain sides but the disturbance and rock fall will kill you
so not many people do that.

What's in the till slopes, eskers and river channels is really HARD stone. Go pick out what appeals to you.
They vary from a cubic yard to pea size, many would make fine hammer heads. Fractured, adze blades.

 

[John Fenna]

Stone is fun
I have done a bit of flint knapping - we even butchered a pig with flint and slate tools - and enjoy carving Old Red Sandstone ... with steel tools though!

 

[Robson Valley]

Yeah! Pig-carving! Oink!!! How I envy that event. Will have to be content with a lump of bison this afternoon.
Already, I have learned to be mindful of where my fingertips are. Close but no damage.
Much to my surprise, flint is not at all slippery when wet.

Nice knapping, John. Did you have a mentor along the way?
Am I right in remembering that Britain has just oodles of flint nodules in the chalk?

 

[Jared]

The group's website, not that it contains much information...

https://cragnorthwales.wordpress.com/excavations/