Limestone is a sedimentary rock composed primarily of calcium carbonate (CaCO3) in the form of the mineral calcite. It most commonly forms in clear, warm, shallow marine waters. It is usually an organic sedimentary rock that forms from the accumulation of shell, coral, algal and fecal debris. It can also be a chemical sedimentary rock formed by the precipitation of calcium carbonate from lake or ocean water.
Because of limestone's biogenic origins, it is often the best rock for finding fossils. The organisms themselves leave fossils in the rock and entire communities and even entire reef structures can be preserved in a limestone bed. At times a limestone is entirely composed of fossils. The rock coquina is a variety of limestone and is composed entirely of fragments of sea shells.
Today Earth has many limestone-forming environments. Most of them are found in shallow water areas between 30 degrees north latitude and 30 degrees south latitude. Limestone is forming in the Caribbean Sea, Indian Ocean, Persian Gulf, Gulf of Mexico, around Pacific Ocean islands and within the Indonesian archipelago. Jura Limestone comes from a boulder quarry in Germany. Jura Grey is an extremly dense limestone which makes it a popular & smart choice for outdoor applications.