Very interesting study done on calcium!

yeah, you just have to be sure of what you are buying, most people I know that use the calcium carbonate buy it by the 50lb bag. I went to get it here locally and could only find the limestone version and Id go through a jar a day of rep cal with all of my critters lol

so what do you use for dusting then?

I work (for an OEM) in the powder processing industry and many of our customers use our equipment to grind Calcium Carbonate (Limestone Variety) and it is usually a much finer grade than what you will find in a Miner-All or Repcal container. I can only imagine that the finer the calcium would be absorbed easier and I am willing to bet if I gather up a retention sample (1/2 Lb or so) from a lab test that the geckos will have no problems with it. Then I could save a bundle on calcium supplements since I have access to many pounds of it on any given day. Where do Geckos get their calcium from in the desert where there are so few calcium powder dishes laying around I ask you?

I use Vionate, Mineral, and Reptivite with a little vionate in each mealy dish too. I also have a jar lid of calcium for them to lick, I am currently using pure calcium from premiumreptiles but their site has been down for a while now so when I run out Ill have to get soemthing different.

If the limestone calcium carbonate is ok to use, Ill get it, I can get 50lbs cheap from the feed store.

Then theres something else at work because the animals are unable to digest calcium carbonate sand. Surface area is the only other things that comes to mind.

Tom, you basically answered yourself here. First its the fact the 'sand' is too large, then its made of calcium which can attract them to eat it. Two bad things, I hate to think how many animals have died or come close, from that stuff.

It is the same ingredient in the powder, it is just digestible as a powder, not a gritty imitation sand. Just think, the equivalent of me feeding you either rocks, or sand. Which one is going to stick?