Wednesday, August 19, 2009

Basic Characteristics of Canadian Placers and Placer Gold

(A gram's worth of Canadian placer gold.)
Common Characteristics

Gold placers throughout the world share many common characteristics in terms of types (i.e., dry, wet, alluvial, elluvial, and so on), their geological geneses (what brought them into being), deposition factors, and overall distribution. 

However, gold placers and the placer gold recovered from them will also display basic characteristics that are singular and unique to a specific nation, region, area, or locale. Canada is no exception to this rule. 

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Here are a few basic characteristics of Canadian placers and placer gold:

Many (if not most) Canadian gold placers were "born" in highly oxidized zones containing moderate-to-substantial vein or lode deposits. (Highly oxidized or "enriched" geological zones are often identified by the presence of sulphides containing iron, copper, silver, manganese, and lead.)

Canadian placers are often the remnants of lode materials formed by supergene processes. (Typically supergene geological processes involve intense pressure, extremely high heat, steam release vents, and the like. For example, much of the gold in California's Motherlode Region was initially formed within a supergene batholith geologic structure.)

Canadian placers of the Tertiary period tend to be shallow in depth but "broader or wider" in terms of overall coverage. (What is meant by "shallow" in terms of actual depth is open to debate. Close to the surface? Shallow overburden? I'm not sure on this, although my read is close to the surface.)

The Yukon and Northwest Territories are noted for producing supergene placer gold that runs as high as .990 fine. (990 fine out of the highest purity level of .999 is exceptional. The closest I myself have come to recovering placer gold this fine was here in New Mexico, where I've recovered placer fines, flakes, and nuggets running close to .917 fine.)

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Mineralization "signatures" in and around Canadian placers may include pyrites, lead, chalcopyrite, stained quartz, rutile, and sericite. (Stained quartz refers to highly mineralized quartz showing various oxidation colors such as red, orange, blue, blue grey, and so on. Rutile is common in many metamorphic rocks while sericite is a finely grained type of micaceous rock similar to feldspar.)

So there you have it. A basic set of characteristics of Canadian placers and placer gold that might prove useful to you out in the field.

Best of luck to all my Canadian mining friends!


(c)  Jim Rocha (J.R.)  2009

Questions? E-mail me at jr872vt90@yahoo.com

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