Fireworks is released at once. Similar to a chrysanthemum, but with long-burning silver or gold stars that produce a soft, dome-shaped weeping willow-like effect. Fireworks pose risks of injury to people, and of damage, largely as a fire hazard. Fireworks produce smoke and dust that may contain residues of heavy metals, sulfur-coal compounds and some low concentration toxic chemicals. These by-products of fireworks combustion will vary depending on the mix of ingredients of a particular firework. (The color green, for instance, may be produced by adding the various compounds and salts of barium, some of which are toxic, and some of
Barium sulfate from barite, which is often highly impure. Barite is processed by carbothermal reduction (heating with coke) to give barium sulfide: In contrast to barium sulfate, barium sulfide is soluble in water and readily converted to the oxide, carbonate, and halides. To produce highly pure barium sulfate, the sulfide or chloride is treated with sulfuric acid or sulfate salts: Barium sulfate produced in this way is often called "blanc fixe", which is French for "permanent white." Blanc fixe is the form of barium encountered in consumer products, such as paints. In the laboratory barium sulfate is generated by combining solutions of