This is just some curiosity of mine regading mining in medieval time in western europe. I know next to nothing about it.
I'll use the site of Largentière, a galeanic mine in Languedoc that was worked between the Xth and XVth centuries, as an exemple as well as the carolingian mine site of Melle (which was the main monetary producer for the era), being understood that it doesn't mean that every mine adopted the same standards of course : just giving a particular comparison point.
Miners generally digged several wheels when needed but they preferred to use the natural outcrops especially if a river was present.
Breaking out trough fire was common enough, breaking the rocks thanks to the heat and finishing the job with masses. The result was tried, then broke before being sent to cleaning and melting (to separate the metals). While limestone mines, as in Melle, prevented issues with groundwater, miners always digged out chemneys for basic aeration.
Note that we're talking of a relatively superficial mining : if it went too deep, if you lacked wood, if it became really impracticable, it could be easily abandoned, even if some metal remained. Some possible mining sites were identified, but not worked until the XIIth century for these (and other) reasons.
From the XIIth onwards, we have something much more structured technically : mechanical support, planified digging (such as getting rid of groundwater trough digged parts) and rationalized pathways. You still had an important relationship between mining and coalmining or woodcoal, and worshops tended to be closer from these IIRC.
Mineral ownership usually depended from who asserted its authority : in Carolingian times, the king; later the various families living there. But with time, you had a lot of agreements between families that accepted to share profits as sort of medieval limited company*, and these agreement eventually included further families (especially royals that tended to replace small families or to pass agreements of pariage with them) but as well urban merchants, financials and bourgeois due to the monetarisation of the economy in the XIIth (partially due to more widesread mining), the need of coins exploded and represented a real financial asset.
*It wasn't uncommon really : you have something similar with urban mills.
Is the miner is a slave worker or serf or maybe something else altogether?
It depends from region to region.
Slavery had largely disappeared in Western Europe, an important exception being Mediterranean regions and coast. I know that Ligurian mines, particularily salt mines, did used slaves in the medieval period, but I can't remember if it was the case in Provence.
More generally, people that worked in the mines were poor sods : not serves (that were tied to the land, but beneficied from not being expellable or that dependent on their lord), but what were called
manouvriers in old and middle french. Basically people that depended on a poor salary (which was inferior to massons, for exemple) to live. They were free all right, but really low on the social scale, and generally didn't remained in the same place during all year.
Some experts (called
argentiers for silver mines in France) were researched for their technical competence.
In addition, peasants (tenants or serves) of the land probably worked on the mining activity from time to time, but not as their main activity (as the coalmining) usually.
If you can any good reference for it?
In addition to what Kaiphranos gave you.
Thanks and apologies for poor english
No problem. Stay on board long enough, and you'll get better.