Quote Originally Posted by Cute Wolf View Post
CaCO3 is pretty much harmless in solid state, and it's soultion had Ksp that was relatively low so it wasn't dangerous either, but prolonged contact with non-rock form of that (especially powder one), could generate enough hydroxide (OH) ions by equilibrium. While sometimes just strong enough to bleach hair pigment, they must wash that thoroughly after got the effect. 1 or 2 day on hair gel (based on pig fat) is maybe enough.
that possibly explains why all the spiky haired fellows in the reconstruction appear to be off white or reddish.