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The granite of the dimension-stone industry along with truly granitic rock also includes gneiss, gabbro, anorthosite and even some sedimentary rocks. Natural stone is used as architectural stone (construction, flooring, cladding, counter tops, curbing, etc.) and as raw block and monument stone for the funerary trade.
"Imperial Porphyry" from the Red Sea Mountains of Egypt A waterworn cobble of porphyry Rhyolite porphyry from Colorado; scale bar in lower left is 1 cm (0.39 in). Porphyry (/ ˈ p ɔːr f ə r i / POR-fə-ree) is any of various granites or igneous rocks with coarse-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate-rich, generally aphanitic matrix or groundmass.
The aged stone has a typical golden hue, but may range in tone from pinkish to off-white. When quarried it is soft and quite workable, but upon exposure it hardens and develops a clear surface that will take on a high polish. Meleke withstands natural erosion very well and provides a high-quality building stone, as well as commercial marble.
Hertfordshire puddingstone is a silica-cemented conglomerate composed of rounded flint pebbles and cobbles with matrix of fine sand and silica cement. The Hertfordshire Puddingstone is characterized by silica-cemented flint gravel that is brown to deep red in colour and often exhibits black exteriors and thin rinds on cut or polished surfaces.
Marleka fairy stone from Stensö in Sweden. Iron sulfide concretions, such as the Kansas Pop rocks, consisting of either pyrite and marcasite, are nonmagnetic. [79] On the other hand, iron sulfide concretions, which either are composed of or contain either pyrrhotite or smythite, will be magnetic to varying degrees. [80]
The following is a list of rock types recognized by geologists.There is no agreed number of specific types of rock. Any unique combination of chemical composition, mineralogy, grain size, texture, or other distinguishing characteristics can describe a rock type.
Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases, [1] [2] is an opaque, [3] impure variety of silica, usually red, yellow, brown or green in color; and rarely blue.
Marble is a rock resulting from metamorphism of sedimentary carbonate rocks, most commonly limestone or dolomite. Metamorphism causes variable re-crystallization of the original carbonate mineral grains. The resulting marble rock is typically composed of an interlocking mosaic of carbonate crystals.