Barium sulfate
From PyroGuide
Formula: BaSO4
Description: Barium sulfate is used as a high temperature oxidizer in some green and white compositions, as well as being the oxidiser in the flash phase of some strobe compositions. It is also used as an additive in many firefly star compositions. Barium nitrate is more common in green pyrotechnic formulas, as it is a more amiable oxidizer and produces a superior colour.
Hazards: Unlike many other barium compounds, barium sulfate is not very poisonous due to its low solubility in water. Indeed it is ingested in significant quantity regularly as a part of some medical procedures.
Sources: Barium sulfate may be precipitated from a solution of a soluble barium salt, such as barium nitrate or chloride, and a sulfate. Magnesium sulfate and Potassium sulfate are both cheaply available as fertilizer and are convenient to use. Magnesium sulfate can be found at pharmacies and grocery stores under its common name as Epsom salt. The precipitated barium sulfate is a very fine powder which may be rinsed by repeated washings with hot water, settling and decanting. A final washing in the filter with acetone or ethanol will allow it to dry quickly, but is not a necessary step. Do not use sulfuric acid to precipitate barium sulfate as this may result in the inclusion of acid droplets in the precipitated particles which can lead to spontaneous ignition in chlorate compositions. There is some debate active regarding the safety of using sulfates in combination with chlorates regardless off acid contamination.