Recovering Gold from Hard Rock
After following all of the clues and searching in all of those places gold might be found, you have managed to recover what appears to be gold. A person who has managed to find and discover what they believe to be gold is naturally very eager to see it as a solid piece of metal.
Such impatience is easily justified by the need to know just what you have found before moving on. A gold bar will be the proof that those tiny flakes or very thin lines inside of rocks really are the precious substance you dreamed about. So, what to do next?
First, before you even think about trying to melt raw gold into ingots, a little chemistry lesson. The melting point of gold is a balmy 1,943 degrees Fahrenheit (1,064 degrees Celsius). Obviously, some changes have to be made before you can melt your gold.
Thankfully, generations of prospectors have figured out how to solve this little problem. You cannot just heat rocks and expect the gold to drip out. First, the gold must be removed from its surrounding material. Today, the big corporations which mine most of the gold have complicated processes and equipment which are far beyond what a small prospector is capable of. Fortunately, methods developed all the way back in the 1840s still work just fine for a casual gold hunter.
Removing the Gold from the Rock
Before beginning the process of removing gold from rock, gather all the essential supplies. In order to break large rocks, a heavy hammer and perhaps a chisel will be needed. A large towel to wrap around rocks when you crush them will also be necessary to avoid losing ore, as well as a bucket for storing broken rock. A mortar and pestle, which may be made of stone or cast iron, will be used to crush the small rocks into powder. Finally, use a flour sifter to further separate the dust from larger particles.
Begin your gold recovery by wrapping the rocks in a towel, and place them on a very hard surface. Then smash them with the hammer until they break into small pieces. Open the towel and remove the largest pieces. Place the smallest pieces into the bucket. Put the larger rocks back into the towel and continue this process until only very small rocks remain.
Take some of the small pieces of rock from the bucket and transfer to the mortar. Use the pestle to crush small rocks into dust. Separate the dust from the larger particles with a sifter and repeat this process until only dust remains. You have now reached the point in your gold recovery where prospectors who were panning for gold in a stream began their process. If you have experience panning for gold, then you will be able to evaluate the way gold acts in your pan, and you will know whether or not that shiny substance is actually real gold or some other mineral.
Also Read: Finding Gold in Quartz Rock
Actual Melting of Gold
There are always a few common-sense reminders when heating anything, such as not trying to melt gold near anything flammable. That may sound like something stupid, but many prospectors have gotten so excited by the thought of seeing their gold, seemingly obvious precautions were forgotten.
Now that your rocks have been crushed to powder, how can you heat it up to 1,963 degrees? That is much hotter than a normal fire, so special equipment is needed.
Flux is a substance used when ores are smelted which acts as a cleaning agent and promotes fluidity. This has the welcome effect of dramatically reducing the temperature of an ore’s melting point. Borax is one substance used as flux, particularly when melting gold and separating it from the surrounding material.
Now, take the fine powder you were left with and mix it with borax. Then place it into a bowl or crucible and heat either with a kiln or an acetylene torch. A simple wood fire should be hot enough to do the job on your new creation.
Once the borax melts, this lowers the melting temperatures dramatically of everything else in the ore. As all of the minerals melt, they oxidize and separate from one another. Gold, however, is not affected by this reaction to the borax and, because of its great weight, will sink to the bottom of the mixture. The oxidized materials and flux combine to form slag which floats to the surface. This can be scraped away once it cools to reveal pure gold hiding at the bottom of the container.
Those rocks with little hints of gold have now, thanks to a lot of elbow grease and some very old school chemistry, been transformed into that precious substance you were hunting.
Next: Classifying Gold Bearing Materials