| What | Value |
|---|---|
| Appearance | Deep red crystals |
| Assay | 97 – 102% |
| Nitrate (NO3) | < 0.05% |
| Sulphate (SO4) | < 0.05% |
| Iron (Fe) | < 0.05% |
| Zinc (Zn) | < 0.1% |
| Substance not ppt by ammonium sulphide (as SO4) |
< 0.3% |