Yes its mostly calcium from what i see, but also a few other ingredients with some vitamins and fiber in it as well. It says on the label there is cactus, carrot and alfalfa in it, so i guess the vitamins come from there.
Havent tried yet, had a small issue to clear up and some adjustments to make in my enclosure before i added anything. I was about to put it in and chuckled to myself when i saw how big it was compared to the tort. "here lil buddy, got ya a mountain to nibble on", lol
I had one of those a while back and my tort didn't even look twice at it... then it started to mold after 3 weeks or so... just my experience though... Hope you have better luck than I did with that!! it seems very nutritional!
My tort never touched it and it just started to mold...your better off using cuttlebone ..this cactus block doesn't do well in hot humid environments our hatchlings need but cuttlebone doesn't mold or decay in those conditions. These blocks are a waste of time and money... Just my opinion