TYPES OF STONE
A very hard, crystalline, platonic rock (formed far below the surface of the earth by slowly cooling magmatic bodies) of various colors consisting of feldspar, quartz (crystalline -2-silica) and smaller amounts of other minerals. Granite is very hard and more resistant to damage than marble, making granite more difficult to harm and correspondingly more difficult to restore than marble. Care of granite is similar to marble except more work is required, however the work is required less often. As a practical matter, a final high gloss finish on granite is generally achieved by using power driven Polishing tools and fine Grit diamonds.
A commercially applied term to any marble, limestone, or dolomite that can take a polish. The term marble is also commonly used by those unfamiliar with different stones to refer to any polished natural stone. Pure marble contains 99% calcium carbonate (CaCO3) and is formed by re-crystallization of sedimentary limestone when subjected to metamorphic conditions. Metamorphic conditions occur in the presence of heat and pressure below the earth’s surface. The limestone melts and crystallizes into marble, a highly compacted crystalline structure with uniformity of grain and hardness which can be polished to a high luster. During this process, minor impurities such as chlorides, sulfur, silicates, iron and organic residues mix into the limestone producing varying colors and veining in the stone.
An agate-like stone often translucent with a layered appearance. It is formed in cold mineral springs by calcite precipitation.
A highly porous rock consisting of calcite mainly from marine sedimentary origin that has not been re-crystallized by metamorphic conditions or precipitated from mineral springs. Some very compact limestone’s may be polished to a high luster.
An ivory to golden brown or reddish colored calcite stone formed over hundreds of thousands of years by precipitation of calcite in hot mineral springs. It comes out of the ground relatively soft, but hardens with age and exposure. It has a sponge-like texture with up to 1/2 inch cavities. These cavities are generally filled with a matching Portland cement when used in construction.
A compact fine grain metamorphic rock that possesses slaty cleavage and hence can be split into slabs and thin plates. It is composed primarily of silica and alumina.