Selenium (metal) powder 99.5% AR (Analytical Reagent) is a high-purity (≥99.5%), grey-to-black metallic powder with a mesh size usually around -100 to -200 (approx. ≤150𝜇𝑚). It is a toxic, non-metal element used in glass, electronics (solar cells), pigments, and metallurgy, soluble in concentrated mineral acids.