In regard to Quartz mines... Will you be using actual quartz blocks, rather than netherquartz 'ore'..? Considering how the netherrack edges make it look like pieces of butchered meat.
I would also like to propose gravel pits, simple stone quarries, definately clay and sandstone quarries, sandpits... Maybe some large 'scavengeable' ruins, which make obtaining mossy bricks, cobble, cracked bricks possible.. Goldmines, mudpits (Soulsand). Glowstone caverns, calcium caves (endstone)..
I could make a case for obtaining other crystal-like rocks, through the use of dyes, or the like..
In regard to 'locating' them.. I don't quite feel the quartz in the human lands. I'd think the humans'd mainly have stone quarries, clay pits, gravel pits, possibly ruins. Other than that, I see humans mainly digging for iron or gold. Possibly 'silver' if it could be made possible.
In the orcish nation, I'd expect to see mudpits, sandpits, gravelpits, sandstone quarries, quartz mines, calcium caves...
The Elves aren't truly miners... Anything beyond basic quarries would be somewhat weird. Though, mudpits, claypits, and possibly glowstone caverns could exist below the forest grounds. Scavengable ruins could also possibly be located here.
The Dwarves should be gettings lotsa kewl rocks and crystals. Obsidian, bloodcrystal (redstone), quartz rock, emeralds, diamonds, iron, gold, glowstone...
Kharajyr would probably fit to have gold and lapis mines below their jungles.. Though, not particulary extensive.
I believe it's mainly about the complexity and size of the mine-works feasible for each race, which should make the difference.
Not as much a 'unique resource' for each race.
Admittedly, it's much easier to just build a different mine for each race with a unique resource.. Though, that does not necessarily mean an economy'd come into existance. Monopolies do not make for a healthy economy.