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.Kennecott Copper Mine, Kennecott, Alaska
For approximately 30 years, the mines produced good ore, some so rich it was simply sent straight to bagging, bypassing milling and loaded directly on the rail cars.
Gold, Quartz & Chalcedony—Part II
The specific gravity of chalcedony is 2.58 to 2.64. This is slightly lower than coarsely crystalline quartz because of slight porosity in chalcedony. Being so light, it will easily wash out of a gold pan.
Sierra County Gold—Part I
...this county contained some of the richest placer ground found in all of California and still produces some pretty impressive finds to this day.
Benches and Fossil Placers
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.
Critical Metals: Copper
From time to time I’ve been doing a series on critical metals and how important they are to our complex and technological society. This month we are going to take a look at copper, and how important that metal is to our modern lives.
Prospecting for Pegmatites
…in some cases pegmatites have produced individual mineral crystals that are enormous, attaining lengths of over 40 feet long, and many of the world’s largest mineral crystals are examples that were found within pegmatite deposits.Why Haven't They Mined This Claim?
Improvements in mining equipment and techniques, along with a higher gold price, make many mining properties profitable today that may not have been in the past.
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