If I understand correctly, when one writes with a pencil, zillions of little graphite particles are pried off the tip of the utensil by the microscopic jagged edges of the writing surface, which hold the graphite particles in place.
How big is a single one of those graphite particles?
I did a quick Google search and, unfortunately, the top best results are documents, so I can’t link to the results. However, when I Google “pencil line electron microscope” I learn that the paper fibers that rip the flakes off are much narrower than 20 micrometers, and I can’t even see the graphite flakes. So in other words, the graphite flakes are really small.
I also learn this is a pretty hot application. This is the direction that research into forgery detection has gone. Someone, somewhere, must have posted the pictures online.
I don’t think you can view graphite in terms of particle. Considering graphite are just layers of carbon sheets stuck together the word particle is probably not the most suitable word.
You said “when one writes with a pencil, zillions of little graphite particles are pried off the tip of the utensil…” a more accurate description would be layers of carbon sheet sliding off the pencil.
As how thin each layer get? The answer is 1 atom thick creating a structure known as graphene. Actually a team in England got hold of some graphite and sticky tape and managed to peel off a layer. This may sound simple but they won a Nobel price for it in 2010 so it probably wasn’t.