An often intricate stone, limestone is a sedimentary rock composed primarily of calcium carbonate. Most limestone forms in coastal regions or lake beds where organic sediment such as skeletal fragments of marine organisms including shells, mollusks, and coral accumulate and fossilize. For this reason, fossils are often visible in limestone. By definition, limestone contains at…

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An often intricate stone, limestone is a sedimentary rock composed primarily of calcium carbonate. Most limestone forms in coastal regions or lake beds where organic sediment such as skeletal fragments of marine organisms including shells, mollusks, and coral accumulate and fossilize. For this reason, fossils are often visible in limestone. By definition, limestone contains at least 50% calcium carbonate along with other minerals such as quartz, feldspar, pyrite, or siderite. Limestone can appear in a wide variety of colors including tan, brown, yellow, red, and even blue, black or gray.

Limestone has been commonly used in architecture throughout history. Many famous landmarks utilized limestone in their construction, such as the exterior of the Great Pyramid at Giza and medieval churches and castles throughout Europe. During the late 19th and early 20th centuries, builders popularized it for use in train stations, banks, and even skyscraper facades in Europe and North America, including the Empire State Building and The Pentagon.

Because limestone is softer than granite, people often opt to use it for vertical areas or floors within their homes or relatively low-traffic commercial areas. Areas such as bathroom floors, vanities, backsplashes, and shower walls are the most popular residential uses. A few varieties of limestone, such as the Jura limestones, are very hard and dense and you may find these varieties in heavy traffic areas, such as airports and malls.

Limestone is sensitive to acids and will etch in their presence. Care should be taken to seal the stone, and cleaning should be done with a neutral cleanser. Most limestone is available only in a honed finish, with the occasional brushed or satin finish. It may sometimes come in a polished finish, but rarely will hold the polish. Cross-cut limestone slabs may show fossils within the stone, and limestone is sometimes vein-cut to show layers.