Diamonds and granite

Diamonds are rare. Some would say their rarity is managed by the producers, others would say they are simply rare, and therefore valuable. I don’t know. Much less, we do not know what their rarity was for the first human occupants who studied the surface minerals and who mined for minerals they found useful. Perhaps they were more plentiful than we imagine. I like to think that was the case, because otherwise I can’t for the life of me figure out how they quarried and carved granite.

Granite Egyptian sphinx at the Louvre, Paris.

I figure there was some ancient Egyptian, call him Josh. Josh wandered over land in northeast Africa and had an eye for diamonds. On a week’s trip in a virgin area, he’d collect maybe a small basket of walnut-size diamonds. He’d take them back to his shop, with a pedestal of granite for a work surface. There he would take a favored wedge-shaped diamond left to him by his father, which was forged to a bronze handle. And with his father’s chisel and a stone mallet he’d split and resplit his week’s finds until they had a nice chisel angle. Then he’d fire up the forge, and weld the new diamond chisel wedges to bronze handles. Once the load was completed, he’d travel to the active quarries and carving shops, where everyone knew his wares. On site he would chip and sharpen the tools they had, to get a few more weeks or months’ use from them. Nice work if you can get it.

Display cabinet for statue of Isis, granite, Louvre Paris. Imagine the difficulty carving the naos–the opening that held the statue.

Granite has a Mohs hardness of 6 to 7. Diamond tops the list at 10. Quartz and flint have a hardness of 7, giving them a very slight edge over granite. Still, given the quality and quantity of granite work from that period I find it very persuasive to imagine diamond as the key.

Diamond particles

We must imagine that diamond particles might have been very useful. A copper or bronze saw would do little against granite unless the kerf were dusted with diamond.

A star drill is the fundamental tool in quarrying. With twist and pound the drill with its four wedges creates holes in stone which, when aligned and then wedged, fractures the stone in a controlled break. Once again, bronze against granite is an exercise in frustration, but if the bottom of the hole is dusted with diamond particles then the cutting should be relatively rapid.

Finding diamond particulates is not a problem, assuming as above, a trip into virgin territory provided the material. Shaping and sizing diamond into tools will create diamond scraps. They can be sized with sieves for different uses. But loose diamond particles readily mix with stone dust from cutting and drilling and mask the abrasive surfaces reducing the cutting power. Can stone dust be removed leaving the diamond particles in place?

OK, this is a stretch, but here goes. Specific gravity of diamond is 3.52. Granite is between 2.6 and 2.9. Wouldn’t it be nice to find a liquid with a specific gravity which, when poured into a mix, would allow the diamond to drift to the bottom but pulling the stone debris up and away from the cutting activity? The element bromine is a brown liquid with a specific gravity of 3.12.

Bromine is very reactive. It is found in many salts, both on land and on coasts, but never as a pure element. It has a very high vapor pressure, so any liquid bromine samples carry a brown vapor cloud above. Were the metallurgists of the Bronze Age sufficiently adept at distillation, thanks to the demand for mercury, that they could distill bromine from its salts? Don’t know. If they did distill it, they’d find it is water soluble. So they might have to distill it with oils, which incidentally would prevent air contact and thereby vaporization. Bronze Age use of bromine is so speculative that it may be easily dismissed, and I would not be distressed. But if I’m quarrying granite with a stone drill, and if a small quantity of bromine down the hole would keep the diamond at the bottom of the hole, and would keep the stone debris removed from the cutting edge, and if a small quantity of oil could keep the stone debris up and away from the cutting action, and if the bromine did not react with the quarry stone, it might make my job a little easier.

Perhaps diamond is the key to quarrying and carving granite. As amazed as I am at the stonework that was achieved, I am just as amazed at the stereotomy–the laying out of the work. I’ll try to tackle that later.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Blog at

%d bloggers like this: