Understanding and Prospecting Benches
September 2011 by Jim HalloranThe most obvious benches are usually near the valley floor, but they can be thousands of feet above the valley floor. Since benches were made by streams, they can contain placer deposits.
I recently had the opportunity to spend a day exploring around Butte, Montana and was amazed by the amount of mining that has taken place there. The old-timers called Butte “the richest hill on earth” and had pretty good reasons for doing so.
The gravels in contact with the bedrock or false bedrock base are often the richest. The same facts apply to the alluvial paystreaks that are formed on gravel bars; the lowest level of the gold-bearing gravel is normally the richest.
...two jadeite locations in California have been thoroughly researched by geologists. There are no doubt others that lie in wait.
One of the first minerals most prospectors learn to recognize is quartz, because, in the right circumstances, it can be an excellent indicator mineral for prospectors. Quartz is common, easy to identify, and is often associated with gold and other valuable metal deposits.
An example of some of this extraordinary ore was a lot of about four tons from the Florence mine during the last days of a lease that averaged over 300 ounces of gold per ton.
I regularly get inquiries along the line of: “Hey, I found this rock, and I think it might be gold ore. How can I tell?” Prospectors are always on the lookout for gold-bearing rocks that may be the source of any nearby placer gold.
Has your experience ever led you to wonder why some gold is deposited on bedrock and in crevices, while other gold is not? We’re going take a deeper look at this and see what we can figure it out.
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