I don’t want to derail the thread, but azomite and other naturally sourced soil amendments don’t necessarily contain large amounts of heavy metals simply because they weren’t created in a lab.
Natural deposits of any mineral can have inclusions of non-target substances, and that can include heavy metals. Deposits with higher heavy metal inclusions are unlikely to make it to market for many reasons (legal, regulatory, PR, etc.). Sodium chloride mines dig salt out of the ground and humans eat it every day. Pink Himalayan salt is pink because of the other 15-70+ trace minerals mixed in.
If in doubt, ask the company for a copy of the lab analysis. Most will gladly send you one if it isn’t already posted on their website. If they refuse, pick a different product.
Re: Azomite for orchids
It is going to wash out of the media quickly and takes years to break down. Good for in-ground growing, not so useful for epiphytes. Terrestrial orchids in a denser mix could theoretically benefit depending on repotting frequency.
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