If you can recognize a robin or a banana by sight, you should be able to recognize single particles of coal, cement or gypsum when the microscope magnifies them to an equivalent size. This is the thesis of those who identify small particles by microscopy. No other microanalytical method identifies such small samples of such diverse substances so quickly.

Single particles of almost any substance - animal, vegetable, mineral, industrial byproduct, raw material, corrosion product, flyash - can be identified in a few seconds to a few minutes by a microscopist trained in particle identification. The particle must be at least 2 to 3 microns in diameter and 10 picograms or 10-11 gram in weight for identification by light microscopy.