A grade quartz: Quartz lumps with clean white / translucent sides and negligible physical impurities, with a silica percentage of around 98% or higher.
1. Oversize (% by weight) using NABL calibrated test sieves of Jayant Scientific = <10%
2. Undersize (% by weight) using NABL calibrated test sieves of Jayant Scientific = <10%
3. Contamination (number) which is visually counted in terms of black and red-yellow particles in ~50 inch2 or ~324 cm2 area = <20
