I have not seen anything related to priming compositions, but:
Iron 2 sulfide, FeS is pyrophoric- If you grind it finely enough, it will spontaneously catch fire!*I would prefer NOT to be the one mixing this into a batch of primer composition.*It's also one of those "indeterminate" compounds, the ratio of Iron to Sulfur in a batch is variable.
Iron disulfide, FeS2 is better known as Iron pyrite- Fool's Gold. It DOES have a history in firearms ignition- As the "flint" used in wheel lock firearms... It definitely does burn.
In mines where Pyrite is exposed to air, modern miners usually dust the mineral's surface regularly with ground limestone to prevent spontaneous combustion.
Iron pyrite in contact with air continuously decomposes into Iron and sulfate, there is a common bacteria that causes this.
http://en.m.wikipedia.org/wiki/Acidithiobacillus
The sulfate combines with any moisture (humidity!) to make sulfuric acid. Sulfuric or sulfurous acids DECOMPOSE CHLORATE.
Before the Lead chamber process, most sulfuric acid was made by leaving heaps of Iron pyrite out in the weather and collecting & concentrating the rainwater running off the heaps- So it's not a good choice with chlorate if you need your primers to be storage stable.
Isn't chemistry fun?