Back 15 years ago was getting diatomite imported from Australia, in small, medium and large sizes, large was 1/2 inch or larger chunks. At the time being promoted as a Orchid potting media. I also tried the small and medium grades for bonsai. Great stuff when used as a component of a mix, not good when used as a sole ingredient, as 100% of the mix. The particular distributor that was importing from the Maidenwell mines in Australia went out of business, I have not found a new source yet, I'm going to check out the link
@jacob letoile supplied, thanks. There are mines in the USA in similar rock formations, obviously as Napa wouldn't import the stuff from Australia. At the time it was thought important that the deposits be of fresh water diatoms, as salt water deposits run the risk of the the product releasing sea salt when first wetted. I'm not sure this ''issue'' is real or the musings of an excessively well read mind that never tested the real products. Some orchids are exceptionally sensitive to salt.
The diatomite holds a tremendous amount of water, and I must warn users that once sifted and used to repot a tree, immediately soak the tree in water to the depth of the rim of the pot in order to saturate the DE, there is a risk that dry DE will pull water out of fine roots, essentially killing off roots if left in contact while totally dry for any length of time. A 15 minute soaking should be enough. This is only a day one issue, once tree is well watered, it won't be an issue again.
Last, as said many times DE is not the same as Turface. Turface is a calcined clay, its composition is over 20% calcium. DE is fossilized Diatoms, who's composition is pretty much all silicon dioxide, there is some calcium but it is less than 5% and bound up as an insoluble with silicates. Key here is in my LOCAL conditions, acid loving plants hate Turface. My water is medium hard, medium amount of calcium, when combined with turface, leads to azalea decline and death. DE combined with my medium calcium water does not add extra calcium, so the total stays below the azalea's limits. My azaleas do well. Similarly Akadama and Kanuma being volcanic clays do not contain much calcium, usually less than 5%.
If you have very low calcium water for watering your plants Turface might be great for azaleas, but I am convinced the combination of medium to hard water and turface will not be a good combination. At least my experience has lead me to this conclusion. I could be wrong, but for what ever reason, in my local conditions turface and azalea don't mix.
