limestone

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A common sedimentary rock consisting mostly of calcium carbonate, CaCO₃, used as a building stone and in the manufacture of lime, carbon dioxide, and cement.

Century Dictionary and Cyclopedia

1. n. Rock consisting wholly or in large part of calcareous material or carbonate of lime. Where, as is often the case, there is some carbonate of magnesia mixed with the lime, the rock is called dolomitic limestone, and from this there may be a gradual transition to dolomite. Marble is the name given to the more crystalline limestones, and especially to such as are solid and handsome enough to be used for ornamental purposes or in costly buildings. Limestones are classed as silicious or argillaceous, according to the amount of sand or silica or of clay they contain. They are of many shades of color, reddish, grayish, and slatecolored tints being the most common. Many marbles, however, are either pure white or slightly clouded with tints of gray, red, or brown; but some are so dark as to appear when polished almost black. The limestone of the fossiliferous stratified groups is generally admitted to have been the result of organic agencies, just as limestone deposits are seen forming at the present time from the debris of coral growth. The crystalline varieties of limestone and marble which occur in the azoic or archæan rocks are by some believed to be a chemical precipitate or segregation, while others consider their existence proof that these rocks, in which no fossils have yet been found, are metamorphosed sedimentary beds, and that this limestone is also the result of organic life.
2. n. A limestone in the New York series of formations, originally called the Scutella and Upper Pentamerus limestones of the Lower Helderberg group of strata. It belongs to the lowest or Helderbergian division of the Lower Devonian, lying near the top, beneath the Port Ewen beds and above the New Scotland limestone. It abounds in fossil remains, and from its purity is highly esteemed both as a construction stone and as a flux in smelting.
3. n. A division of the Lower Silurian of New York State and the adjoining regions, originally termed by Eaton the “Calciferous sandrock.” It is regarded as the lowest member of the Lower Silurian, resting on and graduating by easy changes from the Potsdam sandstone beneath. The rock in northern New York and the Lake Champlain basin is largely a limestone, at times magnesian, and carries a profuse and highly interesting marine fauna. In the Mohawk valley the beds are almost devoid of organic remains, are highly dolomitic, and have been locally designated as the Little Falls dolomite.

Wiktionary

1. n. mineralogy An abundant rock of marine and fresh-water sediments; primarily composed of calcite (CaCO₃); it occurs in a variety of forms, both crystalline and amorphous.
2. adj. Made of or with limestone.

GNU Webster's 1913

1. n. A rock consisting chiefly of calcium carbonate or carbonate of lime. It sometimes contains also magnesium carbonate, and is then called magnesian or dolomitic limestone. Crystalline limestone is called marble.

WordNet 3.0

1. n. a sedimentary rock consisting mainly of calcium that was deposited by the remains of marine animals