- Crystal system: isometric (cubic)
- Crystal shape: octahedron
- Color: transparent
- Stability on air: stable
I prepared the compound by mixing hot concentrated solutions of aluminum sulfate and ammonium nitrate and then cooling the solution:
2Al2(SO4)3 + 3NH4NO3 → 3NH4Al(SO4)2·12H2O(s) + Al(NO3)3(aq)
Alum is much less soluble than aluminum nitrate and crystallizes, leaving Al(NO3)3 in the solution.
More direct way would be using ammonium sulfate (NH4)2SO4 instead of nitrate, but I had no supply of it at the moment.
One of the easiest compounds for growing. Solubility is relatively low (15g/100ml at room temperature), but increases significantly with heating. This makes this compound suitable for quick growing using cooling method.
However, I prefer to use slow evaporation method, as it produces clearer crystals.
The compound is safe.