Leopard Gecko - Oyster Shell Substrate???

I use crushed oyster shells for calcium supplementation in my lettuce gardens.

http://downtoearthfertilizer.com/pro.../oyster-shell/

"A high quality soil conditioner which consists of 96% calcium carbonate and many micronutrients, Oyster Shell provides a long-lasting, steady release of nutrients to help regulate pH levels, improve fertilizer uptake, promote healthy cellular structure and enhance soil tilth.

I have noticed the reptile calcium sands are also calcium carbonate.

This is not a "flour" grade it's more of beach sand grade maybe a tad bigger.

I was wondering if I could keep my adult leopard geckos on this stuff?

I don't see any reason why not as long as it's screened for dust and rinsed well.

I really want to get them back on sand, they seemed to be happier than with the paper towel, but the sand is so darn expensive and I'm almost convinced it's the same material just with a more consistent particle size.