particle size measurement

i asked someone to measure particle size for my calcium carbonate powder. he did and what he gave me as result was 1351.32cm2/g. this wasn't what i was expecting. i expected result in mesh, inches, microns or millimeters. could someone help me make sense of this result? i want someone to help me relate cm2/g to the units above as i can not get a table to do the conversion for me. i want the result in any of the above units.
thank you.