@mike_malaska@deepspace.social
2026-03-11 01:26 UTC
Calcium carbonate has a complex equilibrium that depends on CO2 dissolving in water to make carbonate anion.
Bottom line: the MORE CO2 dissolved, the MORE Calcium carbonate will dissolve in water.
Those fun cave formations? Saturated CaCO3 waters full of CO2 drip into a cave. The CO2 escapes the water, lowers CaCO3 solubiility, now super-saturated CaCO3 (limestone) precipitates out. Cave formations!!!
Straws, stalactites, stalagmites (bounce), helictites, rimstones, etc.
Replies (1)
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@mike_malaska@deepspace.social 2026-03-11 01:30
In the ocean as you go deeper, CO2 capacity goes up. Gas solubility goes up in colder water. And gas solubility goes up in water at higher pressure. So both those effects let more CO2 go into water, and then let more CaCO3 dissolve. (see 3rd post). So you'd think that any CaCO3 in form of calcite (aragonite even more soluble because it's not the most stable form) would dissolve as you go deeper. But....