Damn that soft, white, porous sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite. Calcite is calcium carbonate or CaCO3. Damn that chemistry!
14 posted on 07/04/2016 2:18:23 PM PDT by Scrambler Bob
(As always, /s is implicitly assumed. Unless explicitly labled /not s. Saves keystrokes.)