Borrowed from the IFLS page on Facebook...
The chemistry of 4th July fireworks.
Sodium produces yellow/gold colors. Barium creates green, copper compounds produce blue, strontium salts give you red and titanium metals give you silver-colored sparks.
Other commonly used chemicals are carbon which provides the fuel, oxidizers which produce oxygen for burning, magnesium which increases the overall brilliance and brightness, antimony that gives you a "glitter" effect and calcium which deepens the colors.