| Layering is defined by halite of different colours and grain size with various concentrations of different impurities. |
| Some scientists believe that crystal structure and impurities are central to whether a material becomes triboluminescent. |
| The coke is heated in an oven that has no access to outside air to burn off most of the impurities, leaving a fairly pure form of graphite. |
| The term fluxing also includes the treatment of nonferrous melts by inert or reactive gases to remove solid or gaseous impurities. |
| The filtered water is then treated with bleaching powder to get rid of bacterial impurities. |
| Glass containers such as soda bottles and food jars are easy to recycle because they are free from impurities and have similar melting points. |
