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Yes, I would expect the cherty areas to be more abrasive as well. Any slurry from the chert would probably not break down much to finer size fractions as you hone. That Jnat 'slurry effect' may be...

The white/pink areas look like chert (microcrystalline quartz) that is interbedded with the clays. If so, you may see a difference in the ability to raise a slurry across the surface (possibly less...