The room temperature superconductor has been the "snark" of modern materials science... a substance which transmits electricity with zero resistance, but at normal temperatures, rather than the liquid-helium cooled superconductors of human science.

Unobtanium does not exist in our solar system. It is unique to Pandora. And it is the reason to go there... the pot of gold at the end of the rainbow bridge.

Another interesting property of superconducting materials is that they will levitate in a powerful magnetic field. This magnetic levitation, or maglev, effect has been used to lift trains and run them without wheels since the late 1980's. On Pandora the effect causes huge outcroppings of unobtanium to rip loose from the surface and float in the magnetic vortices. These floating islands circulate slowly in the magnetic currents, like icebergs at sea, scraping against each other and the towering mesa-like mountains of the region. The Pandorans call them the Thundering Rocks, and the entire area is sacred to them.

Which could be a problem, since the humans have come to mine these mountains and get rich. Which is why they are called the Hallelujah Mountains.

Josh stares in awe as they pass over a few of the floating mountains, less than ten miles away on his side of the ship. They float like clouds made of rock, amongst the fixed mountains and swirling cloud structures. Where they are in clear sunlight, they cast hard shadows on the land below.

They are overgrown with foliage at the top, and a straggly beard of vines hangs down beneath them like the roots of an air-fern. The sides are shear cliffs. Waterfalls, originating on the mesa-like tops, stream down the sides and dissolve into spray at the bottoms like upside-down geysers. The local peaks and mesas actually project above the level of the craggy underside of the few floating mountains Josh can see, so it's obvious that collisions are inevitable.