[KClO4] Fine, white powder
Potassium perchlorate is the most commonly used oxidizer in colored pyrotechnic compositions and flash powder. It's also used in whistles, strobes, waterfalls and many other pyrotechnic devices.
This potassium perchlorate's particle size averages -100 mesh (99%). 99% technical grade purity.
Check out the Rainbow of Rubber Stars for a collection of colorful potassium perchlorate based cut star formulas.