I really find the sensation of chalk on my skin unpleasant. Do you have any odd sensory quirks?
I know what you mean but it probably because of it porous, sedimentary texture
Yes, I dislike pumice as well, you're probably right. It's a shame, though, because I enjoy making art with my kids and sidewalk chalk is so easy to clean up. Do you ever draw with chalk?
No but I understand that it is composed of a calcite ionic salt called calcium carbonate
Yes, usually mixed with water-soluble pigments. Are you interested in chemistry or geology? you seem to have a very scientific bent to your conversation. 
yes I am . I like science a lot but another fact is chalk as seen cretacious depoit is unusual amomg sedimentary limestones in the thicknes of the beds
Hm, that's true. Have you ever seen the chalk cliffs of Dover? It's a really striking example of a large natural chalk deposit. 
I can't say that I have in real life but chalk has greater resistance to weathering and slimping than clays