Ah right, I thought you meant the black stuff.
This is what I have now:
Exo Terra - Products : Desert Sand
It just says natural desert sand with no added dyes or chemicals
I am pretty certain that this sand should be fine, and if you are not certain, there is a way to test it. As others have mentioned, some reptile-specific sands have calcium carbonate added to them. (Actually this is unsafe for reptiles for a number of reasons, and so hobbyists are upset that they keep making Calci-Sand). The problem this poses to aquatic set-ups is that it will make the pH more basic over time. If you are not sure if the Exo Terra has calcium in it (and I doubt it does; if it did, they'd try to plug it as a supposed "selling point" in their packaging, you can set some up in a bucket of water. Test the water's pH before adding the sand. Add sand and let it sit for two or three days, then test the pH again. If the pH has become more basic, there is calcium in the sand. (The added calcium in calcium-sands is pretty fine, so unlike with large stones, where we may not know for months if they are going to change our pH, you should be able to tell pretty quickly.)
A lot of companies make "reptile sands" that do not have calcium, but by labeling them "reptile" sand, they can charge more.
For those of you who do keep reptiles, and/or are thinking of it in the future, Calci-Sand really is evil. The powdery calcium particulates can cause eye problems, and it actually sand encourages ingestion in species like leopard geckos who might eat the sand to add calcium to their diet if there's not enough calcium available to them, and the additives in the sand make GI impaction a lot more likely. The sand clumps more readily in their tummies than play-sand would (and they might have been eating more of it to get calcium), and this often proves fatal. With such problems so well documented, I don't even know how they're able to turn a profit on the stuff any more.
