② Sedimentary rocks. Layered rocks formed by transportation, deposition and diagenesis of weathered materials, pyroclastic materials, organic matter and a small amount of cosmic materials at normal temperature and pressure on the surface. According to the genesis, it can be divided into clastic rocks, clay rocks and chemical rocks (including biochemical rocks). Common sedimentary rocks are sandstone, tuffaceous sandstone, conglomerate, clay rock, shale, limestone, dolomite, siliceous rock, iron ore, phosphorite and so on. Sedimentary rocks occupy 7.9% of the crust volume, but they are widely distributed in the surface layer of the crust, accounting for about 75% of the land area, and the seabed is almost completely covered by sediments.
Sedimentary rocks have two prominent characteristics: one is bedding, which is called bedding structure. The interface between layers is called bedding plane, and usually the rocks below are older than the rocks above. Secondly, many sedimentary rocks contain "stony" remains of ancient creatures or traces of their existence and activities-fossils, which are precious materials for judging geological age and studying ancient geographical environment, and are called "pages" and "words" for recording the history of the earth.
③ Metamorphic rocks. Rock formed by metamorphism of original rock. According to the types of metamorphism, metamorphic rocks can be divided into five categories: dynamic metamorphic rocks, contact metamorphic rocks, regional metamorphic rocks, migmatites and metasomatic metamorphic rocks. Common metamorphic rocks include mylonite, cataclastic rock, amphibole, slate, phyllite, schist, gneiss, marble, quartzite, amphibole, schist, eclogite and migmatite. Metamorphic rocks occupy 27.4% of the crust volume.
Rock has specific physical properties such as specific gravity, porosity, compressive strength, tensile strength, etc. It is a factor to be considered in construction, drilling, excavation and other projects, and also a carrier of various mineral resources. Different kinds of rocks contain different minerals. Taking igneous rocks as an example, basic ultrabasic rocks are related to iron-loving elements, such as chromium, nickel, platinum group elements, titanium, vanadium and iron. Acidic rocks are related to ishihara-loving elements, such as tungsten, tin, molybdenum, beryllium, lithium, niobium, tantalum and uranium. Diamond only occurs in kimberlite and K-Mg lamprophyre; Chromite is mostly produced in pure peridotite; The early Yanshanian granite in South China is rich in tungsten-tin deposits. Independent tin deposits and niobium, tantalum and beryllium deposits are often formed in granite in the late Yanshan period. Oil and coal exist only in sedimentary rocks. Iron ore in Precambrian metamorphic rocks is worldwide. Many stones are also important industrial raw materials, such as white marble in Beijing, which is a well-known building decoration material at home and abroad. Rainflower Stone in Nanjing, Shoushan Stone in Fujian, Qingtian Stone in Zhejiang are all good arts and crafts stones, and even river sand and pebbles that are not noticed by people are very useful building materials. Many rocks are also important raw materials of traditional Chinese medicine, such as medical stone (a kind of intermediate-acid dike rock), which is a very popular medicinal rock. Rock is also an important factor in tourism resources. The famous mountains, rivers and grottoes in the world are all related to rocks. Our ancestors have been using rocks since the Stone Age. In today's highly developed science and technology, people can't live without stones without clothing, food, shelter, transportation and medical care. Studying rocks, using rocks, hiding rocks, playing with rocks and loving rocks are no longer the patents of scientists, but gradually become an integral part of the lives of the broad masses.
There are many kinds of stones, but not all can be used. In addition to the aesthetic point of view, what is more important here is whether the chemical composition in the rock will affect the water quality, which will have a negative impact. [2]
1. fluorite
Also known as soft water amethyst, soft water green crystal and fluorite. The colors of stones are yellow, green, blue and purple. When heated, it has glass luster and fluorescence, and the crushed stone slag can be used as the filter material in the filter. In industrial production, it is often used to smelt metal fittings and make fluoride, and can also be processed into low-grade jade. Origin: Jinhua, Zhejiang, Dean, Jiangxi, Longhua, Hebei.
malachite
In fact, it is the tailings of copper mine, with green and shiny color and peacock-tail-shaped circular patterns on the stone surface, hence the name. The copper ions in it will slowly dissolve in water, which will help to supplement the demand of aquatic plants for copper, but it is not advisable to put too much or too much to prevent excessive copper.
3. Hibiscus stone is also called Nanyu and Rose Yingshi. There are rose, light red and white. The main component is silicon dioxide. Produced in Inner Mongolia and Shanxi.
4. Wood fossils
Also known as silicon fossils and tree fossils, 65.438+0.5 billion Jurassic trees evolved into fossils through crustal movement and volcanic ash burial before noon. There are gray, tan, brown and black. Wood fossils in the aquarium can show the vicissitudes of history more vividly. Wood fossils themselves are organic substances, which have evolved into inorganic substances over hundreds of millions of years. Their shapes still retain the outline of trees, and even the annual rings can be clearly seen from the profile, which is incomparable to any other rock. In the aquarium, green aquatic plants can represent the present, dead wood can represent the past, and wood fossils can represent the ancient times. This long-standing historical process is fully displayed in an exaggerated way in a small aquarium. From the aesthetic point of view, aquatic plants, submerged wood and wood fossils belong to the same sex but have different materials, that is, they present a unified composition and contain changing characteristics, that is, harmony and jumping. Wood fossils are rare gems in the aquarium, which are produced in Liaoning and Zhejiang.
5. Black mica schist
It's mica, and black is mercerized. The main component is biotite, which is composed of claystone, siltstone or intermediate-acid volcanic rocks. Compact and exquisite structure. It is distributed all over the country.
6. Lapis lazuli is composed of acidic volcanic rocks and tuff, with jade-like texture, yellow, light yellow and white. Distributed in the south of China.
7. Fish fossils
rock
Also known as tiger skin stone and pine skin stone. The colors are cyan, turquoise, yellow-red and multi-tone, with white spots and holes. Produced in Changxing, Zhejiang. It is made of limestone and should not be used in an aquarium.
8. The stone is grayish black to black with white or gray stripes inside. Named after being produced in Yingde, Guangdong, it is also called Yingde Stone.
9. Chrysanthemum stones have chrysanthemum-like patterns on the surface of white, gray or deep purple stones. Produced in Liuyang, Hunan.
10. Huxian stone is a kind of brown gem with strange shape. Produced in Huxian County, Shaanxi Province.
1 1. Guishi
Also known as wind fossils. It is made of all kinds of broken stones with mixed colors and vertical and horizontal grooves. It is mainly composed of Carboniferous rocks, in which calcium will slowly diffuse into the water, making the water quality hard. So it is not suitable for aquarium use. But it can be used in African aquatic plant landscape. Produced in Geleshan and Tushan in Chongqing, Sichuan.
12. Wu Bi Stone is also called Qingshi. Shi Gang is very hard, so it is named for its crisp and sweet voice. There are black, white, green, brown and other colors, belonging to marble. Produced in Panshi Mountain, Lingbi County, Anhui Province.
13. Kunshan stone is hard, with grooves and small holes. There are yellow and white. Produced in Maanshan, Kunshan County, Jiangsu Province.
14. Xuanshi is white and bright. This stone is hard and has grooves. Produced in Xuancheng, Anhui.
15. Sandstone is also called sandstone. The colors of stones are gray, yellow and green. The stone is hard, with grooves and holes, and it is flaky. Produced in western Sichuan.
16. Melaleuca azurol black and white flaky rocks alternately overlap, and the stone is hard. Produced in Taihu Lake, Jiangsu Province.
17. Pebbles come in various colors. Rivers produced all over the country can be used for African-style aquatic plants landscaping.