... .999%. Used for crystal growth. Specification: ModelVK-L100GVK-L100KCrystal type aaAppearanceWhite loose powderWhite block shapeAPS, um0.2-3--SSA, m2/g6-12 ... , ppm11Fe, ppm22Ca, ppm1 1Mg, ppm11 Application: 1, Single crystal of sapphire 2, Laser Crystal(YAG)and artificial gem 3, Colourful gem 4 ...