Reply #38: That sounds like diatomaceous earth

[eyepaddle]

and oooooohhh boy, no doubt about it, you should've been wearing a dust mask. Not chemically toxic--but pretty high in silica. I've done a lot of work with pesticides--getting rid of waste pesticides for a few different states, and it's a little hard to explain to people, but it truly sucked. Blazing hot, wearing the Personal Protective Equipment (Tyvek Suit and repirator) loading semi trailers by hand lots of dust plus who knows what.

And I hate to say it, that isn't my worst job. (See post below.)