History & Geology
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.
These were the men who periodically picked up the gold amalgam from the tables and sluices in the dredge, processed it, and transported the gold ingots to the railroad express office in Alder. Their trustworthiness must have commanded a prominent wage.
On our last trip, we brought ropes and went down the first waterfall forty vertical feet, only to be confronted by a second, sixty-foot-high, overhanging waterfall that emptied into a slot canyon.
The Beatty Mining District in south-central Nevada has been one of the most productive Mining Districts in the state, producing millions of ounces of gold together with silver, fluorite, mercury and other valuable minerals.
The excitement over IOCG deposits began with the discovery of a monster deposit at Olympic Dam in Australia in 1976. The discovery was accidental as the operator was searching for strata-bound copper deposits.
The large buckets were favorable for the type of ground worked. The gravel was tenacious and compact, due to the existence of irregular pockets of clay.
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.
Only the richest ores could be worked and shipped off for processing at a profit. As a result, early mining in the southern part of the Humboldt Range was short-lived. In the 1880s, placers were discovered in Spring Valley and American Valley on the east side of the range...
The majority of the gold produced in Goldfield has come from ores that are close enough to the surface to be oxidized by the air. This oxidized ore is normally a soft, shattered, earthy material usually stained yellow to brown by oxides of iron.
Because tungsten minerals are heavy, exploration can be done using stream sediment samples. Prospectors looking for gold have found scheelite or wolframite in their placer concentrates, and in some cases this has led them to make important tungsten finds.
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.
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.
…there are loads of different copper minerals, but a large number of them form first in the ground as chalcopyrite and then through the effects of weathering are changed into other minerals like malachite, cuprite and chrysocolla.
In 1983, some of the ore yielded more than 2,500 ounces of gold within 30 feet of the surface. The shoot pinched to a narrow vein.