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I have been trying to find an answer to my question for a couple hours now but I haven't had any luck on Google though I might be searching using the wrong terms I'm not sure as I know next to nothing about mining. Anyway, could it be possible for a mine rich in either iron or copper to also produce some gemstones? I don't mean the big ones like diamonds, sapphires, emeralds or rubies but stones like peridot or turquoise or topaz.

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    $\begingroup$ For clarity: generally precious metals refers to gold, silver, platinum-group metals, and other rare and valuable metals. Iron and copper would both be considered base or industrial metals. Although valuable, they're not as valuable (particularly considered in terms of value per weight). $\endgroup$ – Cadence May 30 '18 at 21:10
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    $\begingroup$ Some kinds of gemstones like diamonds are usually found in the same general regions of the world as precious metals (e.g. South Africa), but I wouldn't know if that holds true down to the particular vein or mine. $\endgroup$ – ohwilleke May 30 '18 at 21:14
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    $\begingroup$ Welcome to WorldBuilding, yukimoda! If you have a moment please take the tour and visit the help center to learn more about the site. You may also find Worldbuilding Meta and The Sandbox (both of which require 5 rep to post on) useful. Have fun! $\endgroup$ – FoxElemental May 30 '18 at 21:22
  • $\begingroup$ @Cadence thank you for correcting me, I guess I had it in my head that all mined metals were called precious metals regardless of how much they're used. $\endgroup$ – yukimoda May 31 '18 at 7:48
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    $\begingroup$ Dwarf Fortress tells me yes, but that might not be trustworthy. $\endgroup$ – JAB May 31 '18 at 16:30
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Sure.

Gems such as diamonds, corundums (ruby and sapphire) come from igneous sources. It's possible that one could have a diamondiferous kimberlite blast through a gold or silver ore-bearing formation, or an intrusive dyke that produces rubies or sapphires to penetrate into a similar formation. It's unlikely, given the relative rarity of the two different commodities, but certainly possible.

As an example that was a near-miss (on a continental scale), the Jericho kimberlite in Nunavut (mined for a few years) is only about 30 kilometers from the Lupin gold mine, and there have been kimberlites in that same area found even closer to the mine.

Amethyst, as another example, is just coloured quartz, and quartz veins provide the source of gold in some mines. I'm not aware of amethyst specifically being found in any gold mines, but it's at least theoretically possible.

For 17 years I was involved in writing agreements concerning minerals rights and royalties and those agreements had provisions to cover the possibility of gemstones being found and produced at a mine for a different commodity.

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    $\begingroup$ Thank you so much for your answer! It actually answered a number of follow up questions I had as well. $\endgroup$ – yukimoda May 31 '18 at 7:04
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    $\begingroup$ I think there's an "in" missing in the last paragraph. I'd add it myself, but it's too short an edit to stand on its own. $\endgroup$ – hBy2Py May 31 '18 at 16:04
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    $\begingroup$ Keith, I have a follow-up question for you. I've read that iron ore is often found in close proximity to gold or copper ore are there any other instances of something like that heppening? Like is silver ore found in close proximity to another type of ore? Or are there gems that are almost always found in close proximity to another metal or gemstone? If I had an amethyst-gold mine what metals or gemstones might realistically be found nearby? $\endgroup$ – yukimoda Jun 1 '18 at 18:43
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    $\begingroup$ Look up "polymetallic deposit". It's quite common. Silver is often found with lead-zinc (also, lead-zinc). The mines in Sudbury produce copper, nickel, gold, and platinum group metals. Indium is a byproduct of tin mines. A mine I worked at was for antimony but had lead and minor amounts of uranium. Olympic Dam in Australia is the world's single largest uranium deposit, the world's fourth largest copper deposit, and produces significant quantities of gold and silver. $\endgroup$ – Keith Morrison Jun 1 '18 at 21:12
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    $\begingroup$ @yukimoda there are natural Electrum veins - a silver-gold alloy. $\endgroup$ – Trish Jun 2 '18 at 13:11
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As you mentioned, there doesn't appear to be a lot of information about this online, but it does seem some gemstones are associated with different metal ores. Quartz is associated with gold and a few other types of veins, and forms a variety of gemstones (amethyst, citrine, rose quartz, etc.), but I don't know if quartz veins actually contain any useful gemstone-quality pieces. (Quartz vein mining appears to be less common today, but was a big deal in the past; most of the well-known gold rushes went after quartz veins.) I'm told beryl (emerald, aquamarine, heliodor) is associated with tin ores.

Aside from this, it's worth noting that some metal ores can be passably pretty rocks in their own right; precious metal ores wouldn't be used that way since they're more valuable processed, but e.g. hematite (a major iron ore) can be either a glossy black stone, which was valued as a gem in Victorian times, or banded blood red/black. Azurite and malachite are well-known semi-precious gems that are also copper ores.

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  • $\begingroup$ Beryl (beryllium ore, with emerald being a specific variety), scheelite (a tungsten ore), and cinnibar (a Mercury ore) are all other good examples of ores with value as gems. $\endgroup$ – Austin Hemmelgarn Jun 1 '18 at 0:02
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Anyway, could it be possible for a mine rich in either iron or copper to also produce some gemstones? I don't mean the big ones like diamonds, sapphires, emeralds or rubies but stones like peridot or turquoise or topaz.

Absolutely. In fact, turquoise, and a number of ornamental stones such as malachite and azurite, are dependent on large concentrations of copper (turquoise is a hydrated phosphate of copper and aluminum).

From Wikipedia:

Turquoise was among the first gems to be mined, and many historic sites have been depleted, though some are still worked to this day. These are all small-scale operations, often seasonal owing to the limited scope and remoteness of the deposits. Most are worked by hand with little or no mechanization. However, turquoise is often recovered as a byproduct of large-scale copper mining operations, especially in the United States.

Also:

Arizona is currently the most important producer of turquoise by value.[5] Several mines exist in the state, two of them famous for their unique colour and quality and considered the best in the industry: the Sleeping Beauty Mine in Globe ceased turquoise mining in August 2012. The mine chose to send all ore to the crusher and to concentrate on copper production due to the rising price of copper on the world market. The price of natural untreated Sleeping Beauty turquoise has risen dramatically since the mine's closing. The Kingman Mine as of 2015 still operates alongside a copper mine outside of the city. Other mines include the Blue Bird mine, Castle Dome, and Ithaca Peak, but they are mostly inactive due to the high cost of operations and federal regulations The Phelps Dodge Lavender Pit mine at Bisbee ceased operations in 1974 and never had a turquoise contractor. All Bisbee turquoise was "lunch pail" mined. It came out of the copper ore mine in miners' lunch pails. Morenci and Turquoise Peak are either inactive or depleted.

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    $\begingroup$ As a "heard it from someone who heard it from someone", another of the mines in the southwest US ended up with large chunks of turquoise, but could not sell it without resulting in a large taxation change from being a copper mine to being a producer of gemstones. The turquoise ended up just being buried under the a leach stockpile. $\endgroup$ – Michael Richardson May 31 '18 at 16:41
  • $\begingroup$ Definitely turquoise and native copper co-occur, see jewelry such as e.g 1 2 $\endgroup$ – Lyndon White Jun 1 '18 at 3:08
  • $\begingroup$ @LyndonWhite jewelry like that is frequently made from turquoise powder that has been reconstituted and mixed with metals prior to shaping and polishing. I'm not sure if it ever occurs naturally like that. $\endgroup$ – Beofett Jun 1 '18 at 13:14
  • $\begingroup$ @Beofett fair enough. Good to know, thanks. $\endgroup$ – Lyndon White Jun 1 '18 at 14:43
  • $\begingroup$ There are some crystalline (and fluorescent) minerals found only in NJ zinc mines $\endgroup$ – John Jan 25 at 15:17

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