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Wall-Rock Alteration
April 2004 by Edgar B. Heylmun, PhD
Wall-rock (country rock) alteration is found in all hard-rock mining districts and has been caused by hydrothermal solutions in the past history of the region. The zones of alteration have a bearing on where one might drill for ore bodies. The weekend prospector does not have the tools nor knowledge to block out ore deposits, but he can narrow down his search dramatically by understanding the zones of wall-rock alteration that he sees.Placer Gold in the Black Hills, South Dakota
During the Indian Wars in 1874, General George Custer and his men camped on French Creek in the southern Black Hills, near the present site of Custer, South Dakota. Two of his men found placer gold in French Creek. Word got out, and before long, a party of prospectors arrived. However, the government had signed a treaty with the Sioux Indians to stay out of the Black Hills. This led to prospectors sneaking in and working creeks all over the region at their own risk.
Quebec Tops Nevada in Survey of Miners
Prospectors and investors looking for a stake in the mining sector should turn to Quebec, as La Belle Province is seen by mining executives as having the best policy environment in the world for investment...
Platinum Group Metals
Platinum is only one of a group of related metals that are referred to as platinum group metals (PGMs), because platinum in its native state usually contains all six metals of the group along with some iron.
Looking Back
Excerpts from California Mining Journal, our original title, published 50 years ago this month.
Silverton Preserving Lofty Symbol of Mining Era

The Tangential Impulse Water Wheel in California Gold Mining History—Part I
The modern tangential impulse water wheel, a device best suited for hydroelectric power production where high water head is available, is an ingenious device born in the historic gold mining industry of California in the 19th Century.
Corralling Those Pesky Platinum Group Metals
Some assay beads disappear, collapse, hide under the surface, or spread out flat while being cupelled, just as the last tiny bit of liquid litharge is driven off. This is especially true of platinum, iridium and osmium, when attempting to re-bead the filtered residue from a parted bead.
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