History & Geology
Can You Recognize Valuable Ores?
August 2016 by Chris Ralph
The process of recognizing ores all starts with being able to recognize some basic minerals and knowing what hard rock ore looks like in the districts where you prospect.
Diary of a Diamond Prospector
I couldn’t wait to get started. With no field budget, an assay budget of $100/year, a 1975-Ford Bronco that was a road hazard, a gas card, a topo map and full support of the director, I headed to the State Line district near Tie Siding along US Highway 287 to begin mapping kimberlite.
Exploring A Historic Lode Mine
Climbing up the debris, I pointed my flashlight up a shaft ascending straight up as far as my light would shine. It was the stope of the pay shoot leading to the old tunnel above!
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.
Large Gold Deposit Types
It is not necessary to have a PhD in geology, but you need to know the basics, so that’s what I am going to try to dig into here—the understandable basics of these gigantic gold deposits.
The Significance of Nuggets in Placers
Chances are better that both types of gold did not come from the same source. Let's look at the probable conditions to cause two types of gold in a placer.
Gold From Cemented Gravels
The truth is that cemented gravels are really not all that complex. There is no mystery of how gold grew there or somehow wormed its way into these solid gravels.
The Birimian Greenstone Belts of West Africa
A few years ago I had a tremendous opportunity to visit Australia and hunt for gold there. The geology of the gold deposits there was somewhat different from what I was used to here in the US. I learned a lot about greenstone belt gold deposits while prospecting them in person, and it was an amazing trip.
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