![]() Dolomite: Dolomite is a sedimentary carbonate rock composed of calcium and magnesium carbonate.Also called "magnesium limestone", it contains from 5 to 40% magnesium carbonate.It is generally very coarse and porous, frequently consisting of oyster and sea shells and fragments. Coquina:Coquina consists of raw, unaltered shell fragments, often quite large, loosely cemented by calcite.Oolite limestone is a sub-category of calcarenite. Some calcarenites contain oolites and if the oolites are present in sufficient quantity, the stone is called oolite limestone. Calcarenite: Calcarenite is composed of sand-sized grains of calcite, usually in the form of tiny fossils, shell fragments and fossil debris.The following definitions are from the American Society for Testing and Materials (ASTM) document, "Standard Definition of Terms Relating to Natural Building Stones." In an effort to improve accuracy in identifying the general categories of limestones at a 'macro' level, the following section contains descriptions of the most common types of limestone, however this information is no substitute for training and experience to correctly identify and catalog stone types. Failure to accurately identify a material to be treated can result in the failure to consider important technical details which subsequently results in irreversible damage to the resource(s). While this is understandable, it does not lessen or eliminate the need to accurately identify the materials which must be treated and maintained. The subtleties which sometimes differentiate between grades and types of stones are frequently beyond the concern and expertise of maintenance workers, building managers and historical architects with responsibility for maintenance of the resources. The actual classification of limestones and marbles can be very confusing to the non-geologists.The same stone can be marketed one time as a limestone and, at another time and place, sold as marble. Oolitic limestone consists of substantial amounts of "oolites" or "ooliths." Oolites are small spherical or sub-spherical grains of concentric calcite. Limestone deposits can undergo metamorphism during major geological events resulting in a recrystallizing as marble. Limestones may vary greatly in texture and porosity from coquina, which is a matrix of whole or pieces of sea shells loosely cemented by calcite, to oolitic limestones and microcrystalline limestones whose structures are so fine that they can be seen only under magnification. ![]() It will effervesce readily in any common acid. It is a soft rock and is easily scratched. Limestone is usually gray, but it may also be white, yellow or brown. Some varieties of limestone have an extremely fine grain. These fossils are frequently visible to the unaided eye on close examination of the stone surface, however this is not always the case. It is commonly composed of tiny fossils, shell fragments and other fossilized debris. Limestone is a sedimentary rock composed principally of calcium carbonate (calcite) or the double carbonate of calcium and magnesium (dolomite). See also 04400-01-S for guidance on inspecting stone masonry failures. This procedure includes general information on the characteristics and common uses of limestone and identifies typical problems associated with the material. Method is the best alternative or compliant with current environmental regulations and safety standards. ![]() Serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or Should only be applied under the guidance of a qualified preservation professional who can assess theĪpplicability of a procedure to a particular building, project or location. We’ve reviewed these procedures for general consistency with federal standardsįor rehabilitating historic buildings and provide them only as a reference. To serve as a resource, not a substitute, for specification development by a qualified preservation Or is compliant with current environmental regulations and safety standards. References to products and suppliers are to serve as a general guideline and do not constitute a federalĮndorsement or determination that a product or method is the best or most current alternative, remains available, All specifications require project-specificĮditing and professional judgement regarding the applicability of a procedure to a particular building, project or ![]() With the Secretary of Interior Standards for rehabilitating historic buildingsĪs understood at the time the procedure is added to the library. Prior to inclusion in GSA’s library of procedures, documents are reviewedīy one or more qualified preservation specialists for general consistency ![]()
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