elevation coincidence Options

[prospect4fun]

Hello, total noob question here:
I've done some gold prospecting so I know how to look for it, but I am totally new to gems. Something I've noticed is that some sites which produce smoky quartz and amazonite, appear to be around 8500'. The diggings around Devils Head, Sentinel/Specimen, StoveMtn, StPetersEureka, even Lake George and Tarryall, all appear to be around that elevation. There's probably many more sites around that elevation that I don't know about, those are just the front range ones I do know of.
Coincidence elevation wise?

Also my recent interest in gems has grown since I started dirtbike riding, which has allowed me to get back in places rarely visited and see some really cool stuff!

[prospect4fun]

Thanks guys! Elevation was about the only thing I could think of that the sites have in common....but something else has started to dawn on me, some of the places I've also noticed a lot of surface quartz, think this is referred to as 'float', which is really obvious around the diggings at DevilsHead, but I've also seen 1950's trails driven right up to quartz outcroppings(along gold camp & 381), tons of milky quartz, but no crystals, and some thorium/uranium ore.
Riding some places is more work than fun, like 672 over Mt.Rosa...once is enough for me.