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 (name here ad-hoc made up in analogy to the above) 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 is known from handling AlN
A passivation layer of aluminum hydroxide might down the reaction.
Then again aluminum hydroxide is quite water soluble.
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.
These should be useful from the hardness perspective and simplicity & symmetry of crystal structure.
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
CaC2 calcium carbide or calcium acetylide
Solidified melt microcrystalline aggregates(?) react
heavily with water as known from carbide lamps.
C2H2 Ethyne aka acetylene gas is evolved.
Not entirely clear if a dense single crystal would behave the same.
especially since calcium hydroxide is not very water soluble. <nr>