I am not sure it does have 1.2g of elemental calcium. This would make each capsule about 2.5g there being two capsules for a serving.
If you have some you can weigh say 10 capsules and see what they are. Domestic weighing machines tend not to be that accurate for light things.
I have some of the non-slow-release kind, and can say they are big, thick, heavy pills. I could even imagine someone choking on one. I stopped taking them a year or so ago just because I decided that amount of calcium in my diet is probably excessive.
I forgot to say that a “dose” is 2 pills.
In which case you are right that could be substantially calcium citrate tetrahydrate. One reason I went to a chemical broker for my citrates was to get certainty as to what I was buying.
