Petrographical properties: structure, chemistry, mineral

Sandstone belongs to the group of clastic sedimentary rocks and consists primarily of quartz grains in the size 0.02-2 mm cemented together by a binder. Sandstones are found in many colors: red, yellow, brown, green. The type of binder (quartz, calcite, clay) determines primarily the strength, water absorption and frost resistance. Sandstone is regarded as easy to work and is found on many older buildings. However, owing to its low abrasion resistance it is not suitable for heavily trafficked floors.
LIMESTONE This is a chemical sedimentary rock that was formed during various geological periods, originally in water - proved by the fossils found in limestone. It consists mainly of calcium carbonate and occurs in various colors, usually yellowish, grey-brown, red or white.Limestone can be used almost universally. Only its use in areas that require frequent cleaning (e.g. entrances, public buildings) or wet areas is not recommended owing to its low resistance to the chemicals used in cleaning agents. Its abrasion resistance differs considerably depending on the particular rock deposit.
Marble, a pararock, is formed by the metamorphosis of calcareous sedimentary rocks. Pure marble is white, crystalline and free from fossils. The crystal surfaces shine in bright light. This stone is ideal for sculpted work with fine contours, but is aallssoo uusseedd iinn bbuuiillddiinngg aass aa fflloooorr finish or wall/facade cladding.
Clay shale or slateThe term shale designates the splitting or cleaving properties of rocks, with the mineral inclusions (clay, chlorite, mica) indicating the degree of metamorphosis. Clayey shale exhibits a sheet-like, parallel structure. It is a very fine-grained, dense stone and usually dark grey to black in color. Its good cleaving ability enables the production of thinslabs just 5-7 mm thick. Owing to the shaley structure, its strength depends on direction. Shales in the form of slates have been used for centuries as roof coverings, cladding and floor tiles.