Human history sure has had its share of “Eureka!” moments.
Language development and our modern human migration out of Africa, both occurring between 50,000 and 100,000 years ago, seem to coincide. Maybe there were earlier attempts to expand into the domain of the Neanderthal that could not succeed until the “Eureka!” moment of acquired language had occurred. For certain, other moments followed.
Circa 40,000 years ago, during the Upper Paleolithic, humans began extracting red ochre from the earth and mining was born, perhaps from deposits like those found in Swaziland and Australia.
Around 10,000 years ago, during the Neolithic period, humans began mining flint for tools and weaponry.
The first known smelting of copper occurred around 7,000 BCE in what is now Turkey and may have been an accidental exposure of ore to heat, perhaps in pursuit of a colorful pigment for decorative purposes.
Recently, at the invitation of Lance Dean, a friend and fellow adventurer across this planet, we engaged in an effort to do some rudimentary smelting. The idea was to take some rocks that I suspected might contain minerals, break them down and subject them to intense heat to see what might be coaxed out of them.
Lance, a retiree living in Elgin, trained as a mechanical engineer, and has had an extensive career around the southwest having worked for mines in Colorado, Nevada, California, Idaho and Arizona. He has traveled every road, either by Jeep or by motorcycle, in Death Valley, with the exception of one because he did not think it an interesting route.
In Lance’s well-appointed workshop, acetylene is the carbon fuel of choice to obtain the heat needed to induce a chemical change in the ore. The setup consists of the fuel tank and an oxygen tank side by side. Hoses feed the fuel that burns and the oxygen that accelerates it.
I crush the first bit of rock that I have chosen with a ball peen hammer. The rock is from the waste rock pile at a former gold mine. I think that it might be promising because it has a quartz/limestone contact zone, with red staining that could be iron and I know that iron sometimes rides with gold. The crushed heap is on a thick 7” diameter round piece of heat treated steel. This will be our forge.
The acetylene valve that feeds the gas to the tip of the brass nozzle is opened. A spark lighter is squeezed and a piece of steel strikes a flint, makes a spark, and a deep throated whoosh signals that a jet of gas has ignited. To get the flame focused and under control the compressed oxygen valve is opened and suddenly the wildly vacillating and black smoking flame becomes a cone with a point. Within the cone is another, smaller, more intense burning cone with a smaller tip and this is where the business will be done.
After a minute the heat source is removed. The remains, a combination of ash and glasslike orbs, are worked over with a paint scraper and the hammer. Everything crumbles into smaller pieces. Nothing solid is left, just dust.
The second rock that I chose to work on had been collected from the same waste pile. It has some very nicely formed quartz crystals stained with what appears to be yellow sulfides. We bust this specimen up and subject it to the torch. This rock pops and flakes with what looks like tiny sparklers going off. Lance notes that we may be igniting the sulfur. We are heating to what Lance guesses is over 2000° F, but nothing runs out. I again pound on our previously molten, but now cooled heap, and try to separate out any hard, non-crumbling bits. I see what I think might be pyrite but the pieces are too small to isolate. We decide to heat it again and this time I work the torch.
The reheat yields nothing of interest, but now I’ve learned the importance of welding goggles in keeping a persistent red dot from forming and obscuring my field of vision.
For my last try I go into my Planters Nuts can to retrieve some small rocks that I have hacked out of a mine wall. The mineralization is more obvious. The pieces are a combination of malachite green and azurite blue crystals, indicative of copper.
I hesitate to sacrifice them to the fire-god at the tip of the brass-nozzled acetylene torch but I am deeply curious about what I have collected, about what I can discover. I decide to put this batch to the flame. The ball peen hammer strikes and crushes the blue sparkles into smaller sparkles.
This time we coat the sample with a flux of Borax which is meant to let the heat in but coat the mineral content to prevent it from oxidizing.
I strike-light the torch and bring it to the ore slowly, and from above. The sample gives off a different flame this time. It has a soft green hue.
When the firing ends, and the small bubbling rock cools, I take the hammer to it. This time there is a small glassy orb that when struck, shatters, but leaves behind a hard, spherical pellet. The pellet, when struck, does not crumble. When struck again, harder, it flattens a bit.
Lance, seeing this, exclaims, “By God, you’ve got a piece of metal!” I don’t know Greek, but I think that statement can be crushed down to “Eureka!”