Stone is a kind of material processed from rock or rock with artificial synthetic properties equivalent to rock, including marble, granite, slate, sandstone, etc. Stone has a high position in decorative materials, and it has irreplaceable decorative properties, which can show the noble temperament of buildings.
This article selects some common stone terms, and briefly shares the main types and characteristics of stone for every stone person and interested friends to refer to.
1、 Introduction to some nouns
Magmatic rock: Rock formed by condensation of magma, also called igneous rock.
Sedimentary rock: Rock formed by the consolidation of sediment.
Metamorphic rock: rock formed by metamorphism of original rock.
Granite: deep acidic magmatic rock mainly composed of quartz, feldspar, mica and a small amount of other dark minerals.
Limestone: Sedimentary rock mainly composed of calcite.
Marble: metamorphic rock with carbonate minerals (mainly calcite and dolomite) greater than 50%.
2、 Main types of stone
Nowadays, the commonly used stone materials are divided into four categories: sedimentary rock, metamorphic rock, igneous rock and artificial stone.
1. Sedimentary rock
Sedimentary rocks are separated from the detritus of glaciers, rivers, winds, oceans, plants and other organisms, deposited to form rock deposits, and consolidated under high temperature and pressure for millions of years.
(1) Limestone: the main mineral composition is calcite. Mineral particles and crystal structures are rare, with smooth surface and small particles. The hardness varies, and some dense limestone can be polished.
(2) Sandstone: it is formed by quartz particles, with stable structure, usually light brown or red, and mainly contains silicon, calcium, clay and iron oxide.
(3) Saponite: It is formed by various talc and is very soft. It is a wear-resistant compact ore and is not easy to produce stains.
(4) Fossils: Natural fossils containing marine shellfish and plants, which are considered as limestone.
(5) Travertine (pore stone): usually cream or light red, it is formed by calcite deposition in hot springs.
2. Metamorphic rock
Metamorphic rocks are naturally metamorphosed from one stone to another under the mixed action of high temperature, high pressure and minerals. Metamorphic rocks may be recrystallization, texture or color change.
(1) Marble: It is a recrystallized limestone, which becomes soft under high temperature and pressure, and recrystallizes to form marble when the contained minerals change. The main components are calcium and dolomite, with many colors, obvious patterns and many mineral grains.
(2) Slate: metamorphic rock formed from clay rock and sedimentary shale (sometimes quartz stone). The mineral particles are fine, thin and fragile, usually black, gray or green.
(3) Serpentine: It is named for its snake skin like patterns. The most common colors are green and brown. The Mohs hardness is between 2.5 and 4. It contains a large amount of magnesium and is derived from igneous rocks.
3. Igneous rock
Igneous rock is mainly formed by volcanic materials, such as magma, so it is also called magmatic rock. After the liquid magma under the surface cools and solidifies, mineral gas and liquid infiltrate into the rock to form new crystals and various colors.
Granite: mainly formed by quartz (35%), feldspar (45%) and potassium, generally dark color. Calcite is very little, if any. The texture is very hard and easier to maintain than marble, but there are still small holes and stains. According to the mixing proportion of quartz, mica and feldspar, granites are divided into different types.
4. Artificial stone
Artificial stone is made of non natural mixture, such as resin, cement and gravel adhesive.
(1) Terrazzo: marble and granite fragments embedded in cement mixture.
(2) Condensed stone or aggregate stone: marble fragments are embedded in colored resin mixture.
(3) Cultural stone or imitation stone: paint on the resin mixture or mix with the paint, which looks like marble.
3、 Some Characteristics of Natural Stone
1. Fire resistance
All kinds of stones are different. Some stones are chemically decomposed under the action of high temperature. Gypsum is decomposed when the temperature is higher than 107 ℃, limestone and marble are decomposed when the temperature is higher than 910 ℃, and granite is cracked when the temperature is 600 ℃ due to uneven heating of its constituent minerals.
2. Expansion and contraction
Stone also expands with heat and shrinks with cold. However, if it is cooled after being heated, its shrinkage cannot be restored to its original volume, and part of it must be retained as permanent expansion.
3. Frost resistance
Stone in the wet state can resist freezing and thawing without significant damage, which is called frost resistance. The water in the pores of the rock freezes when the temperature is as low as - 20 ℃. The water in the pores expands by 1/10 larger than the original volume. If the rock cannot resist the force caused by this expansion, it will be damaged. Generally, if the water absorption is less than 0.5%, its frost resistance will not be considered.
4. Compressive strength
The compressive strength of stone will be different due to such factors as mineral composition, crystal thickness, homogeneity of cementation material, loading area, angle between loading and cleavage, etc. If other conditions are the same, usually the compact materials with fine crystalline particles and bonding with each other have high strength. The compressive strength of dense volcanic rocks after drying and saturated with water has no difference (extremely low water absorption). If they are porous and water repellent cemented rocks, their dry and wet strengths are significantly different.