Water reactive gemstones
Aluminum based water reacting gems
– Al4C3 evolves methane on contact with water => aka methanide (~Mohs8) – AlN aluminum nitride evolves ammonia on contact with water => ammonianide (zincblende or wurzite structure or stacking mix – Mohs 8-9)
While these react strongly in form of powders
this is not the case in the form of bulk crystals as
a passivation layer of aluminum hydroxide slows down the reaction.
This may be less clear in the aluminum carbide case with
more volatile methane and no(?) experimental data.
Properly enclosed these gems can also be used in filigree form.
Can be good for intentional degradability, albeit releasing aluminum
in the form of aluminum hydroxide that eventually making aluminum salts
is not a typical natural occurrence anc can cause ennvironmental problems
if released in too high quantity and too short time making fro too high local concentrations
Calcium bases water reacting compounds
– CsC2