Calcite is usually identified by using the acid test. The test is done by putting some drops of weak hydrochloric acid on a sample. If the sample fizzles or reacts, it is calcite.
Rocks such as marble and limestone also fizzle during the acid test. This is because they contain calcite.
Calcite, a carbonate mineral, is characterized by its Mohs scale hardness of 3 and specific gravity of 2.71. It is usually colorless or white. The presence of impurities can give it shades of red, yellow or gray. Calcite is found naturally in marine organisms' shells as well as in stalagmites and stalactites.