Simmering Granules for Fragrance Oil Burner Have Chemical Odor?

I recently bought 2 small bags of simmering granules for my oil burners. I have been using oil in them, but decided to try these. However even though I put a tsp in my burner it seemed to give off a chemical smell. The ones I bought were baby powder and vanilla. Does anyone know what they are made from, before I use them again? Many thanks.

Helen xx

By helen