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Mass fraction of sulfur — not less than 99.98%
Mass fraction of ash — not more than 0.02%.
Mass fraction of organic matter — not more than 0.01%.
Mass fraction of acids (expressed as sulfuric acid) — not more than 0.0015%.
Water content by mass — not more than 0.2%.
Mechanical impurities — not permitted.
Bulk density — within the range of 1.04–1.35 g/cm³ (often around 1.25 g/cm³).