599A vs 601A

The samples look very similar. The only noticeable differences are that:

(1) 601 has some areas with slightly coarser grains. (See bottom photo here.)
(2) 601 has (very) slightly more clumping of the "dust". Both samples though have very nice (uniform) distribution of the dust phase.

Here are 4 photos for comparison (2 each 599 and 601) that show grains very clearly.

599A_01

599A_08

601A_05

601A_09