Posted 12 July 2006 - 03:51 PM
look like a decent chunk of copper ore, maybe sulphide cap (the grayish part on top). sulphide ore will set a detector off.
Copper oxides are greenish looking, copper and silver sulphides are bluish/purple. Copper sulfate is also a bluish purple (think of "2000 flushes" toilet disinfectant. Other copper sulphides and porphyry ore may be brownish stains, peacock copper, or grayish. some high grade copper ores are silvery brass or even black, and weighty.
There may be gold in it, but probably not visible yellow gold.
worth? hard to say with fluctuating copper prices, but would be to the ton of rock. specimen may also contain some silver.
All is not lost however, gold occurs in the vicinity of copper and silver; copper vice versa; silver maybe, maybe not. Most gold placer is an alloy with silver in varying percentages. All of this stuff is what makes arizona famous in the mining world.
huge copper deposits carrying silver and gold values is the arizona calling card, and practically the only other area that has like deposits on a large scale are Sonora & Chihuahua mexico. Granted, there are some big pits in Utah, Nevada, Montana, but not statewide
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IT SEEMS that we always seem to find what we are NOT looking for...