## Calcium carbonate

**Formula**
 
$CaCO3$

**Pyrotechnic use**

Colorant

**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.

**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.

**Hazards**
 
Xi

Dust may cause irritation to eyes, skin or respiratory system. Wear gloves, protection goggles and dust mask when manipulating fine powder.