Calcium carbonate[]
Formula: CaCO3[]
Synonyms: Precipitated chalk, Limestone, Calcite, Carbonic acid calcium salt.
Description: Colorless powder. It slowly reacts with NH4ClO4 in presence of moisture. Calcium carbonate is often used in toy fireworks as a cheap substitute for strontium salts, but the flame is reddish orange and not so beautiful as e.g. with SrCO3.
Hazards: Dust may cause irritation to eyes, skin or respiratory system. Wear gloves, protection goggles and dust mask when manipulating fine powder.
Sources: A cheap source is the ceramics supply. Price is about $3/kg for the technical grade. you can also get it easely by powdering clean egg shells.
Hazard Symbols: Xi