History & Geology
The Amazing Mineral Tourmaline
December 2013 by Chris Ralph
It is a gemstone, and yet it is also closely associated with many types of metal ores. It's valuable itself but often points toward other valuable minerals—that is certainly something prospectors want to know more about!
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.Ask The Experts
Gold in clastic black shale
Calcite and Limestone
The other distinguishing feature of calcite has to do with its chemistry. Geologists sometimes take a small bottle of dilute hydrochloric acid out into the field with them because calcite reacts with acids to make a bubbly foam.
Ask The Experts
Sulfides and oxides—what's the difference between the two?
Alaska Gold: Lisianski Inlet's First Bonanza
In 1967, a local resident showed me a pouch of small gold nuggets and flakes. Several years later I asked the same person where that gold was found. He responded, “From the streambed below the old stamp mill at Apex.”
California's Mother Lode Quartz Veins
The actions of the hot, ore-bearing solutions are not limited only to the deposition of material within the walls of the fissures.
Fabulous Florence—The Golden Town of Idaho
In September 1861, on a round-about prospecting journey homeward, five California gold miners discovered gold in the area now called Florence. While watering the horses, one of the men noticed a golden color on a piece of slate bedrock in the stream...
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