The material used in fireworks is a dark grey powder called "fuzed" silicon and usually passes 240 mesh showing about 5% of impurity. It is mainly used for hot primes in combination with potassium nitrate or gunpowder, forming ignition compositions for special devices such as waterfalls with high Al content, or stars which are likely to blow blind. Once ignited, such primes produce a hot molten glass droplets and assure ignition of the main effect. They produce quite high temperatures, for the melting point of Si is 1420 deg C.