Flour substance or a drug?

I found a bag of something (somewhere). It had a flour consistency. And when I touched it it stuck to my fingers. I am concerned that it may be cocaine. I was snooping when I found it but it was in plain sight. This person I don't believe would do drugs and they use things like epsom salt in baths so it could be something like. All I know is that is was white and had a flour consistency and stuck to my fingers when I touched it. If it's not cocaine what else could it be (not other drugs) but legal things. I also don't need any lecture about snooping I know what I did and my conscious is not concerned at all.