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That Thar Gold

April 17, 2015

You might remember this picture from Wednesday. It’s a chunk of gold-bearing quartz. Let me tell you about it.IMG_9946

(Bear in mind that this is, once again, me working off my memory of research waters I’ve only dipped my toes into, so what I’m about to say may be 99% wrong. Here’s hoping, though.)

So gold isn’t that common an element, and when it’s not sitting near the top of the crust tempting miners, it’s lurking near the mantle, dissolved in very, very, very hot water along with other elements and molecules. Any hot spots in the crust, like with the friction at plate boundaries or near volcanoes, is also going to have gold dissolved in water. Water fills any cracks it finds, and when it’s inevitably pushed far enough from the mantle (or other heat source), it cools off and the molecules in the solution precipitate out, forming solids. This is how we get a lot of veins of crystals and metals, I think, but this is especially, for the purposes of this post, why gold and quartz tend to be found together.

IMG_9941

B.C. has a lot of gold. Less now, after 150-odd years and nine gold rushes, but still. Lots of gold. A fair bit of it is in quartz, but a fair bit is also “placer” gold, which means it’s nuggets found in creeks and rivers. That gold gets there because, once the veins of gold are inevitably pushed to the surface, glaciers come along and scrape off the top of the crust, dropping it into the gouges and depressions they leave when they melt—like the Fraser River.

But why does B.C. in particular have so much gold? Because it also has a really hot and violent geologic history. Lots of islands smashing into the mainland to form mountain ranges. Lots of volcanoes resulting from the smashing. Lots and lots of chances for gold to precipitate out of boiling water. Lots of gold did.

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B.C. wouldn’t be a province if it wasn’t for the gold rushes. The gold rushes wouldn’t have happened if there hadn’t been volcanoes. Thanks, volcanoes!

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2 Comments leave one →
  1. Harold Rhenisch permalink
    April 17, 2015 5:18 pm

    Nice ore there! Great synthesis! Thanks.

    • anassarhenisch permalink*
      April 17, 2015 10:02 pm

      Welcome! Anytime.

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