a specimen can be tested with dilute hydrochloric acid. If the sample bubbles vigorously, the sample contains the mineral???
If it is limestone the mineral is usually calcite. But almost all carbonate mineral reacts with dil HCl, so it is not conclusive. To identify the rock, you have to study its petrography (mineral composition, texture etc.) Another diagnostic feature about limestone is its weathering pattern. Being very soft and very susceptible to chemical weathering, the exposed limestone will form grooves of various shapes and sizes.
a rock that vigorously fizzes when in contact with HCl contains the MINERAL calcite (which is CaCO3, calcium carbonate). also, dolomite will fizz with acid, however not as vigorously. Dolomite is a Mg/Ca carbonate. Usually you can tell if it is dolomite if you 'powder' the rock first, then it fizzes.
Halifax,Nova Scotia , Canada
