Bornite
Bornite is a mineral that is found in several areas of the world, but was first described in the 1700s in the Bohemian region of present day Czechia. Composted of the elements copper, iron, and sulphur — chemical formula: Cu5FeS4 — it is an important ore of copper. This rock feels ever-so-slightly heavy for its size; not remarkably heavy, but just a bit, because of the copper and iron it contains.
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Bornite naturally ranges from brown to reddish-brown in color. But, because this mineral is composed primarily of copper and iron, both of which oxidize readily, bornite has the tendency to tarnish easily. When that happens, it can turn beautiful, almost iridescent colors with patches of blue, green, gold, and pink. This property has earned it the fitting name of "Peacock Ore." The following photo shows the same piece of bornite pictured above, but with oxidation present.
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In some specimens, the oxidized colors can be even brighter!
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Goethite • Smoky Quartz • Tibetan Quartz • Amazonite Beads • Zoisite
Rutilated Quartz • Garnet • Amazonite Sphere • Lapis Lazuli Mala
Amethyst Point • How Rocks Get Their Color • Red Jasper
Ring, Ring! Amethyst Calling! • Lapis Lazuli • Turitella Agate
The same oxidation process is often seen in statues and domes of buildings which have been constructed of copper or bronze. The following photo of Kaiser Wilhelm I — King of Prussia, the first German Emperor, and the first Head of State of a united Germany — illustrates this greenish tarnish, which is referred to as verdigris (pronounced: VER' - duh - gree, as it is a word borrowed from the French, and the ending "s" is silent). The grayish areas on the statue are the original color, and the green patina is the verdigris.
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What I call the reverse ("back") side of my bornite specimen has splotches of magenta, vivid pink, and aqua, which were much more pronounced when I got the stone a decade or so ago. I suppose I should put it outside, let it oxidize again, and re-shoot it... LOL! 😁
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SOURCES
1 Wikipedia: Bornite
2 Wikipedia: Verdigris
3 Wikipedia: Kaiser Wilhelm I
4 Pixabay: Statue of Kaiser Wilhelm by Tama66
Rutilated Quartz • Garnet • Amazonite Sphere • Lapis Lazuli Mala
Amethyst Point • How Rocks Get Their Color • Red Jasper
Ring, Ring! Amethyst Calling! • Lapis Lazuli • Turitella Agate
When I saw the word, "Bornite" my brain said, "you know this word" but refused to tell me from where. Then you said, "Peacock Ore" - EUREKA! I have a handful of pieces stuffed in a box somewhere (blergh, I'm such a bad witch...LOL), and I've always loved the shiny colors! Now I know how to "refresh" them if they're angry with me for being hidden from the light for so long - thanks, @thekittygirl!
Such a cool stone! I used to study geology but never kept up with it. It is a fascinating subject though. Thanks for sharing!
I must admit @thekittygirl that it's an interesting mineral and its colors makes them really unique. That's the good part of Steemit: you can learn new things everyday. Great post!
That's a cool rock!! I love geology. I really like going out and finding the gems and minerals myself. For me it started with looking for gold, but later spread to finding all kinds of cool minerals. Recently I've been working on chiseling out some Corundum rubies. But I also just learned of a spot where a buddy of mine is finding really nice big garnets... I think I'm gonna have to check it out. lol. I have never heard of Bornite, so this was really interesting. Thanks!