Limestone

Limestone is one of the most versatile, useful stones we know. In its pure form it is hard enough to be used in counters, floors, paving, surface re-facing, and recently it has been incorporated into stone home furnishing items such as coasters, tables, and chess boards. Other forms of limestone include chalk (a much softer version), and marl (a type of fertilizer). Travertine is also a limestone, though harder, that often can be found in stalactite and stalagmite form in caves. Limestone is used to produce lime, to help extract iron, and in many concretes. Its applications widely vary.
Limestoned is chiefly composed of calcium carbonate and, being a sedimentary rock, it is formed by the collection of other minerals coming together to bond at a structural level. It is white in its purest form; however impurities that become stuck in the structure during formation cause colorful streaks and shades to appear in its surface. Iron will generally cause the colors to shift to red, or yellow, while carbon will shift the colors more towards grey or black. The erratic nature of these colors makes each piece of limestone unique. It is, however, grouped into named quantities of similar stones.
Caring for limestone is easy. It is generally best in a low traffic indoor setting. Certain stone treatments can be used to seal the stone, and if you are interested in these you should ask a local stone professional for their advice on the right sealer to use on your stone.