Grind Size ..... Homestake Mining Sand .....

[Heavy-Black-Sand]

Although it is finely ground in water, Homestake sand can be cyanided by gravity leaching to yield a high extraction of the gold. Sieve analyses and assays reveal that the finer the sand the higher the extraction. This varies from better than 90 per cent in the minus 200 mesh material to less than 50 per cent in the case of particles coarser than 50 mesh ......

https://archive.org/details/cyanidehandbook00clenrich/page/n5/mode/2up
Publication date; 1910