I am IN NO WAY advocating for rock sucking. At all. I'm just wondering.
Rock have minerals.
Grug need minerals.
Rock have minerals.
??
Plus I might just be a complete retard but occasionally I'll see a rock and some part of my monkey brain wants me to put it in my mouth. What do you think? Based and rocksuckingpilled or retarded?
Your average river rock is almost entirely silicon and oxygen by mass.
Gypsum has a lot of calcium in it, but if you wanted that, you'd need rocks stratified with gypsum deposits.