It's interesting when you go to a site with a lot of different colors of limestone: fancinating! When I was a brandnew in geology, I did ask a stupid question to a field geologist "what color limestone should be". He answered me in a fashion like a lecture, from vary basic to the end. Unfortunately I did remember at all.

I then found the answer myself, easy and simple see the following:

It is ordinarily white but may be colored by impurities, iron oxide making it brown, yellow, or red and carbon making it blue, black, or gray.

I have done some geological and hydrogeological assessment for karst aquifer. Karst is a type of landscape, and also an aquifer type. Karst areas consist of solid but chemically soluble rock such as limestone (most important) and dolomite, but also gypsum, anhydrite and several other soluble rocks. The chemical reaction describing limestone dissolution is:

CaCO 3 + CO 2 + H 2O = Ca 2+ + 2HCO 3 -


whish this could clarify if you have any confusion between karst and limestone.