So I'm shopping around for some vermiculite or perlite. Pretty much whichever I can find locally. What am I looking for it to say so that I know it's pure?

I found this one at Home Depot. The MSDS says it's "considered practically non-toxic" as far as risks from ingestion go. The composition is Perlite, Urea, Ammonium Phosphate, and Potassium nitrate, KNO3. Anyone use this one? Do you think it'd be OK?

Or am I looking for something that specifically only says perlite or vermiculite in the ingredients list? Does it need to be certified organic?

Thanks!