Granulated nickel slag is essentially an angular, black, glassy slag "sand" with most particles in the size range of − 2 mm (No. 10 sieve) to + 0.150 mm (No. 100 sieve). It is more porous, with lower specific gravity and higher absorption, than air-cooled nicked slag. Nickel slag is very abrasive and does not lend itself well to grinding.