It seems sometimes like the whole world focuses on Gold…
… but there are other previous metals to hunt, and since they are quite a bit more prevalent as a % of the Earth’s crust, then it can be more rewarding on a regular basis to hunt them, practically speaking.
The “big three” have traditionally been: Gold (Au), Silver (Ag), and Copper (Cu), with some starry-eyed individuals probably on the lookout for Platinum (Pt). If your local geologist says that there’s no prior evidence of significant Platinum where you are looking, then you might want to listen to them…
… On the other hand, Gold, Silver, and Copper are very much so “where you find them”, and the recent re-discovery of the true Lost Adams Diggings in New Mexico proves this time-honored point.
And speaking of “big”, Ag and Cu and their important ores can form pretty big masses, like this 52.8 lb. chunk of Silver-Galena ore recovered with a metal detector. The entire pocket yielded over 80 lb of ore, and could have been just sitting there on the surface since the dawn of civilization or before…
Figure 2 – A huge nugget of Silver-Galena ore recently recovered with a metal detector. The density of the material feels amazing when you pick it up, and it’s outward appearance has earned it the nickname “the meteorite”.
Though not even remotely close to being pure Silver (wouldn’t that have been nice?), “the meteroite” is amazing as a specimen piece. Similarly, the common Copper ore, Chrysocolla, is very pretty to behold.
Figure 3 – Beautiful blue Copper ore, Chrysocolla; this is a hydrous form, and dries out quickly if not protected.
Part of the allure of metals, however, is their unique visual appearance, and since they are far more rare in pure form, it’s a special treat to get at them as close as possible to being in a “native” state. If pure enough, native Silver can be revealed easily with a toothbrush and some soapy water.
Figure 4 – Bright native Silver was revealed on this rock simply by brushing off the oxide with a toothbrush and soapy water.
Other common forms of Silver ore, though chemically almost pure Silver, have very different properties than the native form. For example, Acanthite is Ag2S, close to pure Silver by weight, but is much harder than Ag alone.
Figure 5 – A vein of Acanthite (Ag2S) was recovered right on the side of the road in a thoroughly-prospected mining area through use of a metal detector; Acanthite has very different physical properties than Silver, even though they are almost chemically identical.
Hunting for native metals and metallic minerals can be time-consuming and use up a lot of personal resources. For example, a “lost” mine thought to be quite closer to the main road recently took over 4 years to finally locate, even though it was a significant producer in the 1800’s, many people claimed to know its location, and the local School of Mines had “clear” records to it. As it turns out, all resources available were miles off and even on the wrong side of the drainage. Once finally located, the mine could not be mistaken, and the ore proved rich indeed. The saga of just this one hunt is lengthy, and an eventual partner in the search had looked for it decades earlier, before its recent re-discovery, braving the canyon full of bear-sign and back-country peril in the very same quest.
Figure 6 – Gold ore recovered as float below a rich “lost” mine. Black arrows and dots drawn on the rock point to visible free-milling gold. The mine took 4 years to finally locate due to inaccurate official records, but once found, the mine proved to be as described in the 1800’s.
High concentrations of rare elements are by definition anomalies, and the interesting things that nature has done to create valuable deposits can be quite complex. Take for example certain types of Copper deposits formed by deposition of Copper and Silver in ancient plant material; the net result is the equivalent of petrified wood (replacement/pseudomorph, technically) that is composed primarily of Copper and Silver!
Figure 7 – Copper and Silver ore formed by replacement of Carbonate plant matter results in the equivalent of very dense petrified Copper/Silver wood. The thought of such specimens being melted down is painful, but society needs a lot of Copper to function!
Another example of the apparently anomalous is the combination of metallic mineral deposits with radioactive mineral deposits. One such example is a type of Nickel-Skutterudite, Silver, and Uranium deposit that may seem perfectly reasonable to a geologist, but which would probably not be the first guess of most people answering a trivia question.
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