Historical Background
Mineral History: The minerals of calcite, pure calcium carbonate, and limestone, mostly calcium carbonate also with lime (calcium oxide), have a long history. Limestone and Calcite minerals make up 4% of the earth’s crust. Limestone is itself a record of the earth’s history since it is made up of ancient shells and coral, which are made of calcium carbonate, which were once in an ocean. Calcite is also a record of the earth’s history since it can preserve fossils and artifacts, like those found in Tutankhamen’s tomb. (http://www.touregypt.net/featurestories/kv52.htm) Some of the artifacts found from the ancient pharaoh’s tomb are made of calcite like canopic jars and two calcite lamps found that display its important property of double refraction. (See uses page for how this property is useful or the structure page to learn more about the property itself)
History in Marine Life: As previously mentioned calcium carbonate makes up the shells in the ocean and coral (for more information on this see abundance page). These organisms have been in oceans being protected by their shells and skeletons, which are made stiff by the calcium carbonate contained in them, for millions of years.
History of Chalk: Chalk is made of calcium carbonate and has been being used as a writing tool for over 10,000 years. (see uses page) Chalk is a white fine-grained limestone that is found in deposits at the bottom of oceans, its source also being the old shells and coral in seas. Chalk deposits occur mainly in shallow water, so in areas where there are many chalk deposits it can be deduced that the ocean once there was shallow.
History of Caves: Caves are formed by water with dissolved calcite and limestone that over a long period of time drips in the caves and the limestone and calcite and other minerals become solid again. The size of the stalactites and stalagmites formed by the cave can tell its history because the take many years to form.