A microcrystalline material is a crystallized substance or rock that contains small crystals visible only through microscopic examination. There is little agreement on the range of crystal sizes that should be regarded as microcrystalline, but the extreme range of values suggested is 1 to 200 microns. See also Macrocrystalline Nanocrystalline silicon Microcrystalline cellulose Microcrystalline wax Protocrystalline Rock microstructure References Mineralogy concepts Petrology