Emerald

Emerald is the mineral on which the survival of the entire human race depends on. Its unique properties allowed humans to survive on giant floating landmasses. Scientists have been studying this mineral for ages.

Properties
The emerald has the ability to levitate objects depending on its Levitational energy (see picture). It can be crushed to dust and mixing it with steam will produce emerald gas, which is used in airships.

Somehow, when you link an emerald physically with a solid object, it will push on the object in the reverse way of gravity. Some side-effects: Dizzyness when inhaled/eaten, reacts explosively with Phosforus and Aluminium, and it tends to pull towards other emeralds, in a sort-of magnetic way.