History & Geology
Benches and Fossil Placers
March 2013 by Jim Halloran
Unfortunately for us mortal humans, we have a poor perspective on geologic time. When we look at a landscape such as a stream valley, we see it only in two, or at the most, three dimensions. We have poor comprehension of the valley’s fourth and most important dimension—time.Prospecting for Surface Flood Gold Placers on Low and Intermediate Gradient Streams
Sample panning is a very important method used to find the richest parts of a flood gold deposit before setting up equipment and running material.Hard Rock and Placer Gold of Manhattan, Nevada
He found 5 to 7 feet of gravel containing half an ounce per yard. This started a rush of placer activity and several other shafts were sunk, with some large multi-ounce nuggets being found.
Natural Gold Alloys
Natural gold is never 100% pure; all natural nuggets contain at least some impurities. We're going to take a look at just what some of those impurities might be.
Green Valley Gold District, Payson, Arizona
Most gold-bearing quartz veins found in the district were fracture fillings in faults enclosed by crushed quartz zones along their margins. Since the host rocks were often extensively weathered, portions of the veins stood out as positive, resistant outcrops. The gold-bearing veins ranged from a few inches wide to the vein at the Gowan mine that was as much as 12 feet wide. Mining Pegmatite Deposits
With successively lower temperatures as the water mixture cools, new sets of minerals are formed and many of those stable at a higher degree of heat became subject to alteration as the temperature progressively moved lower.
The Birimian Greenstone Belts of West Africa
The country we were to visit was Burkina Faso, a small country about the same size of my home state of Nevada with about 10 times more people. The second day I was in Africa, we went out to the goldfields for the first time.
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