History & Geology
The Robinson is a wooden bucket-line dredge that was built in the early 1900s in New York and shipped in pieces to Nash County in North Carolina by train for reassembly.
Because the forces of erosion and gravity tend to carry lighter materials like quartz away more easily, the heavy minerals like gold or silver will tend to be concentrated in the general area around the vein outcrop. These concentrations are what make residual placers so attractive.
What also helped keep Coulterville alive was the fact that the town itself happened to be sitting on top of one of the richest veins in the Mother Lode. The ledge itself was three hundred feet wide.
I didn’t know what to expect because the area we were working was not close to the water, but we were pleasantly surprised when we began to pan out some nice flakes and a few pickers.
There are a number of characteristics that are used when one identifies a mineral. Each characteristic gives an indication as to what the mineral might be, and the combination of them will point to what it is.
These deposits are very widespread across the planet. In fact, they are so extensive that something around 75% of all the gold ever mined comes from these types of deposits (if one includes the placer deposits that also formed from them).
Nevada produces about 75% of all the gold mined in the US. This means that all the other 49 states combined only produce 25%, and this includes California, Alaska and Arizona.
…we focused on various layers of hard-packed flood material out of the creek, and we also obtained some material up quite a ways from the creek itself on bedrock.
How rich does a hard rock ore have to be for it to be worthwhile to process and extract the gold?
Many prospectors thought that Nevada was all prospected out following all the rich discoveries of the 1860s and 1870s, and what was there to be found had already been found.
You can learn a lot from a small mining operation because you have to become proficient in every job. Soon I was preparing fuses, placing powder (dynamite) and learning the ins and outs of drilling and blasting.
Prospectors often wonder why gold deposits in veins like it does. Why is one vein rich while another is barren, even though they are only a few hundred feet apart?
A few months later, a young, greenhorn lawyer agreed to pay to have it assayed, and the quartz turned out to be rich in both gold and silver.
The small-scale miner has reasonable opportunity to exploit some of these small, rich placer gold deposits.