February 2024 by Ray Mills
The big interest to prospectors thinking about the effect of erosion is not what might happen long into the future, but what they might find in the rivers later this summer when the water levels go down.
Ground sluicing, surfacing and scratching are a few names given to the recovery of gold in shallow areas. Where I live, the hills are dotted with small surface diggings.
Some of the items that I’m going to go over are outcroppings, ditches, exploratory trenches and contacts/surface materials. I am going to speak about each of the above items in as much detail as I can, and then towards the end of this article I will tie them together.
Excited for this first notable evidence, I returned to that riverbed, looking for another paystreak and obviously more jade.
This concept of detecting does not always work as we sometimes get a week or so where the temperatures rise to 116°—sometimes more.
The whole purpose of sampling mineralized ground is to measure the values in a small volume of material that would be representative of a much larger volume of similar material. The key word is representative. Chemical and fire assaying will not accurately represent placer deposits by themselves.
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.