Answer :
Limestone is composed mostly of calcite (calcium carbonate) and often formed from marine organisms, whereas dolostone is primarily dolomite (calcium-magnesium carbonate), commonly resulting from the alteration of limestone. So, correct the option is D. Limestone is mostly calcite, and dolostone is mostly dolomite.
The difference between limestone and dolostone is primarily based on their composition. Limestone is mostly composed of the mineral calcite (calcium carbonate, CaCO3), and it often forms from the remains of the skeletons of marine animals. Limestone can also contain visible shells of marine organisms that have accumulated on the ocean floor. On the other hand, dolostone is mostly composed of the mineral dolomite (calcium-magnesium carbonate, CaMg(CO3)2). It forms as a chemical precipitate or from the alteration of limestone. To distinguish, limestone typically reacts with dilute hydrochloric acid by effervescing or fizzing, while dolomite reacts when ground into a powder.
Both limestone and dolostone are sedimentary rocks that form under similar conditions such as evaporation and precipitation. Dolostone derives from limestone when magnesium-rich fluids circulate through the limestone and initiate a process called dolomitization. This alters the composition of the limestone, and thus, dolomite or dolostone is created.So, correct the option is D. Limestone is mostly calcite, and dolostone is mostly dolomite.
