I am interested in how gem stones were mined in the early to late middle ages, I'm most interested in medieval times since there was a general lack of mechanized equipment, and in most areas chemistry was just barely beginning and surely was not sophisticated enough to extract minerals.
Were gemstones just found incidental to mining for known precious metals? What techniques were used? How was the ore processed for stones as opposed to crushing or leaching ore for metals? I am fascinated and perplexed with how and where gemstones came from in this early era of mining especially since gemstones in jewelry was such a major status symbol. How does one go down a torch lit tunnel and come out with a rough stone?
Any GENERAL information on the gemstone trade during these times is also welcome. Thanks
I'm a hobby gemcutter and rockhound. I can't cite any ancient sources, but there aren't many "torch lit tunnels" in modern gem mines, there were probably few or none in the past. One of the defining characteristics of gemstones is their hardness- resistance to abrasion. This means that they can survive long journeys in river gravel, then be picked out of gravel bars. Look at modern alluvial gem mines of Sri Lanka, presumably very little has changed.
How was the ore processed for stones
It still isn't, except for diamond mines. Diamonds withstand a trip through a rock crusher, other gems don't. Most colored stones, like emerald, ruby, topaz, aquamarine, or amethyst are found in Vugs, small open spaces in the host rock, where uncommon elements remained in liquid form as the rock solidified (usually this was superheated water under high pressure, rather than lava). These vugs are scattered randomly, can often appera as a paper thin vein, which is actually a sheet that extends into the rock and randomly opens into pockets with larger crystals. Working this kind of mine, even with modern tools, is an artisanal operation, you can never tell when a strong hammer blow will crush a fragile vug just below the surface.
Finally, some actual citations- not by me, but from other in a question I posted to a lapidary forum about how ancient lapidaries shaped and polished stones.