... , non-toxic, not insoluble in water, difficult soluble inconcentrated acid and alkaline3) Application: widely used in productions of monocrystal, photo-luminescent ... pigment, fluorescent powder, high pressure lamp tube, high alumina ceramic4) 99.99% grade, 99.999% grade5 ... 0.5 - 40um6) Loose density: 0.25 - 0.6sqm/g High Purity Alumina