I never heard of it and don't take it, but I did just Google it. I personally don't take any additional calcium supplements anymore. Excessive calcium in the system may end up in the arteries causing blockage and stroke. When I did take calcium, I used citrate form. Carbonate form is definitely undesired.
Instead, I try to make sure that the calcium I do get via foods, stays in my bones and not my arteries by taking a vitamin k2 supplement https://www.springboard4health.com/notebook/v_k2.html
. I'd rather have a broken hip than a major stroke. I also take vitamin D3 daily...magnesium citrate also.