Bismuth subcarbonate
From PyroGuide
Formula: (BiO)2CO3
Synonyms: Bismuth oxycarbonate, Basic bismuth carbonate
Description: Bismuth subcarbonate is a fine white to yellow-white powder used mainly in Crackling microstars (Dragon eggs) as a substitution for Poisonous Lead tetraoxide and expensive Bismuth trioxide
Hazards: Bismuth subcarbonate is not particularly hazardous. However it is a skin, eye and respiratory system irritant. Wear gloves, dust mask, protection glasses, and do not ingest. Large ingested amounts can cause systemic bismuth poisoning with symptoms of headache, skin rashes, kidney damage, and rarely mild jaundice.
Sources: Bismuth subcarbonate can be purchased from Pyro suppliers.