That means that the different types of metals used in the stars each have a characteristic color. Here are some of the metals and specific compounds that are typically used in fireworks to produce different colors: Red: strontium (strontium carbonate, SrCO3), for intense reds and lithium (lithium carbonate, Li2CO3, or lithium chloride, LiCl) for medium reds. Orange: calcium (calcium chloride, CaCl2)