It cost me 12 bucks for a 5 kg bag and half was rubbish. I might use a fly screen next time and end up with a bit more but not much.
Also maybe 5 % of the larger pieces have been treated with a nice smelling blue chemical . I am sure this will simply wash out quite quickly. The pieces of diatomite are blue there is no other foreign material.
I soaked some in a glass of water and it stayed solid as a rock, I'm 99 %confident it's good shari.

I will be on the lookout now for bigger bags with hopefully less dust .
Anyway beggars can't be choosers and I am stoaked to get my hands on some diatomite.
Pictures will follow of the product.