Originally Posted by
Woodash
IMO, it's not only the flatness of the particles, but the fact that the particles tend to slide past each other (again, think talcum power) which further minimizes abrasion.
The larger particles that you see in the Jnat slurries that are the ~same size before and after working are very likely quartz grains and not the clays. Quartz is very resistant to alteration. If you look closely, you can see that the clays are the particles that have a 'pseudo-hexagonal' shapes. Beautiful examples of this are in the raw Jnat slurry, and even in the worked slurry as well (note that you may not see perfect hexagons, but you can frequently see ~120 degree angles between particle edges).
The components are (in relative order of abundance):
Quartz >
Illite (mica) >
Chlorite (clinochlore) >
Interstratified illite-montmorillonite (not shown) >
Albite (feldspar) >>
Goethite (trace) >>
Noncrystalline silica (not shown).
Anyway, I hope someone finds this useful.