In Desert Mines, there is a rare chance of coming across Oases. This contains Water, Mud, Tropical Trees, and regular Grass.
But those things you can get anywhere, so while this is a cool addition, there's no point in searching for one, like there is when searching for Cavern Mines in Mountain Mines.
So, I think it'd be a cool addition to add something specific to these Oases; an Oasis Gem.
This gem would be found only in an Oasis, and only one per Oasis.
It'd look something like a Blue Topas gemstone. Just the size of a regular block. Could be in cube-form, or not.
Anyways, yeah. Add it? Thanks. :)