Calci-sand harmful?

Well I have lost two scorpions so far for no reason, that were both on this substrate. In fact they were the only two I've lost. Both developed mycosis but neighboring scorpions of the same species did not. One was Mesaensis, the other an Australis. Both were kept at 30% humidity. At least that was the humidity right outside the enclosure. I am going to throw a RH meter in there to see what is really going on. My prego Australis is right next door and she seems plenty healthy but is on high dollar sand.

There may also be spores present in the sand that the scorps are picking up. Or its getting in the booklungs and causing nasties?

If you really want to test if there's spores, try sprinkling some sand onto syrup and seeing if it gets any fuzzier than syrup that hasn't had any sand added to it.