White or light-colored crystals with a relative density of D₄²º=1.769, can be decomposed at 235 ℃, soluble in water ( acidic aqueous solution), insoluble in ethanol or acetone, will become pieces after moisture absorption and release ammonia when acting with alkali.
（一）Caprolactam grade: byproduct of caprolactam
Usage：Mainly used as fertilizer for various soils and crops; also can be used in textile, leather, medicine and as nitrogen sources for yeast fermenting.
（二）Ammonium pyrosulfate: byproduct of coking.
Quality standard：N-≥20.5%；Water -≤1%。
Usage : mainly used for making compound fertilizer, potassium sulfate, ammonium chloride, ammonium persulfate, etc. , can also be used for rare earths mining.
Technical specifications（China National Standard CGB535-1995）
Note: When the ammonium sulphate is used for agriculture, it is not necessary to check the content of Fe, As, heavy metal or water insolubles.