Limestone

Limestone is a sedimentary rock, composed largely of the minerals calcite and aragonite, which are different forms of calcium carbonite. The nature limestone formation causes it to be part of some of the most elaborate cavern structures in the world, including the Carlsbad Caverns, Luray Caverns, and Mammoth Caves.

If the limestone is pure it will be a white color. The different colors that can be seen in limestone come from impurities in its structure; an iron oxide impurity will make the stone yellow, red, or brownish. Carbon impurities will turn the stone blue, grey, or black. The nature of these impurities means that limestone could come in hundreds of differently colored combinations, and each stone will look different from others, even in the same cave.

Chalk is one form of limestone, although softer then usual. Marl is another, a form of fertilizer. Marble is formed by the metamorphisms of limestone. Limestone is also used as a flux in the extraction of iron, as a source of lime, and in certain concretes. It is widely used in flooring, counters, and in home furnishings including clocks, hot plates, tables and more.