Limestone is a rock with a diversity of uses. It could be the one rock that is used in more ways than any other. Most limestone is made into crushed stone that is used in road base, railroad ballast, foundation stone, drainfields, concrete aggregate, and other construction uses. It is fired in a kiln with crushed shale to…

There are many different types of limestone – each with its own name. These names are often based upon how the rock formed, its appearance, its composition, or its physical properties. Here are some of the more commonly encountered types of limestone. Chalk Chalk is the name of a limestone that forms from an accumulation of…

Limestone is by definition a rock that contains at least 50% calcium carbonate in the form of calcite by weight. All limestones contain at least a few percent other materials. These can be small particles of quartz, feldspar, or clay minerals delivered to the site by streams, currents and wave action. Particles of chert, pyrite, siderite, and other minerals…

Limestone can also form through evaporation. Stalactites, stalagmites, and other cave formations (often called “speleothems”) are examples of limestone that formed through evaporation. In a cave, droplets of water seeping down from above enter the cave through fractures or other pore spaces in the cave ceiling. There they might evaporate before falling to the cave…

Many limestone-forming environments are active on Earth today. Most of them are found in shallow parts of the ocean 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. One of these areas is…

Some limestones form by direct precipitation of calcium carbonate from marine or fresh water. Limestones formed this way are chemical sedimentary rocks. They are thought to be less abundant than biological limestones. Most biological limestones contain significant amounts of directly precipitated calcium carbonate. After the biological grains have accumulated and are buried, water that is…

Most limestones form in calm, clear, warm, shallow marine waters. That type of environment is where organisms capable of forming calcium carbonate shells and skeletons can thrive and easily extract the needed ingredients from ocean water. When these animals die, their shell and skeletal debris accumulate as a sediment that might be lithified into limestone.…

Limestone is a sedimentary rock composed primarily of calcite, a calcium carbonate mineral with a chemical composition of CaCO3. It usually forms in clear, calm, warm, shallow marine waters. Limestone is usually a biological sedimentary rock, forming from the accumulation of shell, coral, algal, fecal, and other organic debris. It can also form by chemical sedimentary processes, such as the precipitation…