Napa auto parts sells a pure 100% DE under part number:8822
I use this in my Bonsai applications.
"it lead me to contact a mineral mine in Nevada and I found out that NAPA auto parts sells their freshwater diatomaceous earth as an oil absorber.
It is 100% Diatomaceous earth and is sold under the NAPA store brand name and comes in a 25 lb bags. it is around 6$ per bag and works awesome!! Make sure to get the 25 lb bag and double check the back of the bag and make sure it says diatomaceous earth in the small print. NAPA Auto Parts stores are all over the US and anyone should be relatively close to one."
You can also use it by rinsing the small size rocks and making a spray with a water bottle. "the murky water that is left after one initially rinses the diatomaceous earth for the first time is actually a mechanical pesticide. I spray the liquid on my trees if they get aphids and the aphids are gone the next day. The sharp microscopic edges of the Diatoms cut through the exoskeleton of the insect causing them to dry out and die."
Now this is in small crushed form, not pulverized and powdered.
hope this helps.