淡蓝绿色结晶或粉末。在空气中逐渐风化及氧化。能溶于水，不溶于乙醇。浅蓝绿色结晶或粉末，对光敏感.

二、质量标准

GB/T 661-92

项目Item                                                                     
   分析纯                              
化学纯

                                                                                            (AR)                           
      (CP)

含量［Fe(NH4)2(SO4)2·6H2O)Assay,%                    
≥99.5                            
99.0

高铁(Fe)Ferric,%                                                          
   ≤0.01                            
0.02

铜(Cu)Copper,%                                                       
       ≤0.002                        
  0.01

锌(Zn)Zinc,%                                                                     
≤0.005                       
   0.02

铅(Pb)Lead,%                                                          
         ≤0.002                       
   0.004

氨水不沉淀物(以硫酸盐计)Substances not

precipitated by
ammonia,%                                              ≤0.1                               0.2

pH(50g/L溶液，25℃)                                                       
3-5                                   3-5

水不溶物Insoluble matter in
water,%                            ≤0.005                         
0.02

氯化物(Cl)Chloride,%                                                         
≤0.001                       
0.005

磷酸盐(PO4)Phosphate,%                                             
   ≤0.0005                      
0.002

锰(Mn)Manganese,%                                                       
  ≤0.05                             
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三、用途

用作分析试剂，测定卤素时用作指示剂