MSO4NH4OH−−−−−→↓XwhiteNH4OH−−−−−→excessYH2S−−→↓Z. Here M and Z are:
Cu,ZnS
Zn,ZnS
Fe,FeS
Al,Al2S3
ZnSO4NH4OH−−−−−→Zn(OH)2White ppt↓NH4OH−−−−−→[Zn(NH3)4]2+Soluble complex(aq)H2S−−→ZnS↓White ppt
Here X,Y,Z are respectively