white and shiny square crystal,can easily volate in the air. proportion:3.59-3.95g/ml SeO2 Cu Ni Co S non- water-soluble98% 0.002 0.002 0.001 0.03 0.20Purify:≥98%Application:It is suitable for the manganese electrolytic additives, the trace elements additives, black agent of iron and steel materials, but also for the oxidant, catalyst, chemical reagents, etc. SeO2 selenium dioxide