Peridotite

Classification：Igneous Rock

An ultrabasic intrusive rock is the main rock type of the mantle. It is mainly composed of olivine and pyroxene. The unmetamorphosed peridotite is usually dark green, but most of them are serpentine rocks formed after metamorphism of peridotite.

Peridotite is a rock that exists in the upper mantle. When the ocean closes, the mantle will produce an outcrop. That's why we encounter it in the mountains, such as the Alps, which usually becomes serpentine. Peridotite can also be lifted under volcanic action, so we can sometimes find it in basalt and volcanoes.

Mineral composition:
Peridotite is a kind of ultrabasic intrusive rock. It is mainly composed of olivine and pyroxene. Olivine content is 40% to 90%. Pyroxene is orthopyroxene or clinopyroxene. Sometimes it contains a small amount of amphibole, biotite or chromite. The color is dark green, with granular structure, reaction boundary structure, includes structural, sideronitic texture. According to the variety and content of pyroxene, it can be further divided into trapezite (mainly composed of olivine and trapezite), monoclinic pyroxene (mainly composed of olivine and clinopyroxene), and Er Hui (monoclinopyroxene and trapyroxene are almost equal in content). Under a certain temperature and pressure, the effect of the heated fluid is altered, such as after hydration, olivine becomes serpentine and brucite; after silicification, olivine becomes serpentine, and magnesium olivine becomes serpentine and magnesite under carbonation. Minerals related to it include chromium, nickel, cobalt, platinum, asbestos and talc. Pure, transparent, crack free, olivine green olivine can be used as a gemstone. Olivine gem deposit has high economic value.

Peridotite is an olive green, magnesium rich silicate rock, mainly composed of olivine, followed by pyroxene, sometimes containing a small amount of chromite, magnetite, ilmenite or pyrrhotite. Olivine belongs to the trapezoid system, and the crystal is thick plate like, usually granular aggregates. Olive green to yellow green. Glass luster. The hardness is 6.5 to 7, and the density is 3.2 to 3.5 grams per cubic centimeter. Mainly produced in the ultramafic and mafic igneous rocks, easily altered to serpentine. Peridotite is a fully crystalline self form or granular granular structure. Its pure PeridotiteMgO content reaches 49%, and its melting point is as high as 1910 degrees Celsius. Peridotite is less fresh and easy to turn into serpentine. The density is 2.94 to 3.37 grams per cubic centimeter. The tensile strength is very high, and it is resistant to alkali. Peridotite is often associated with pure Peridotite, pyroxenite and other ultrabasic rocks and basic rocks, and is mainly formed in orogenic belts.
It is a kind of ultrabasic intrusive rock. It is mainly composed of Peridotite and pyroxene. The content of them is approximately equal. Most of them are medium and coarse structure. Fresh rocks are black green or near black. The surface of the surface is easily weathered to form serpentine. Tibet, Qilian Mountains, Inner Mongolia, Ningxia and Shandong provinces were found in China.

Structural features:
Olivine and pyroxene of ultrabasic rocks.
Olivine is usually of olivine and Peridot; pyroxene is plagioclite and monoclinopyroxene; a small amount of minerals include pomegranite, mica, and plagioclase; the accessory minerals are chrome spinel, ilmenite and other metal minerals. Diamond, graphite, silica, zircon and other minerals have also been found in some ultrabasic rocks in Tibet, China. In chemical composition, Peridotite is characterized by SiO2<45%, alkali and magnesium rich iron. The fresh rock is olive green, with granular structure, mosaic structure, containing (olive) structure, network structure, inter filling structure, sponge iron structure, variable crystal structure, dissolving structure and twisting structure. The alteration of Peridotite includes serpentinization, carbonation of talcum, green slime fossilization, transpermeability, sub flicker, hydric and magnesium fossilization, etinfossilization, soaping and silicification, among which serpentinization is the most common. In the process of serpentine, olivine is mainly composed of chrysotile and orthorhombic pyroxene is sericite.
According to the type and relative content of pyroxene in Peridotite, it can be divided into Fang Hui Peridotite, Shan Hui Peridotite and two Hui Peridotite. When the original rock is horned amphibole appeared transition to hornblende Peridotite or amphibolite. Peridotite can form separate rock mass or independent lithofacies, rock enclaves of Xuan Wuyan and Kimberley rocks, and residual upper mantle rock fragments at the bottom of ophiolite suite. The minerals related to Peridotite include chromite, copper nickel ore, vanadium titanium magnetite and platinum ore.
This kind of rock is commonly referred to as ultrabasic intrusive rocks. Is black, dark green or yellow green; hypautomorphic granular structure and granular mosaic structure, massive structure. The main minerals are olivine and pyroxene. Secondary minerals are hornblende, biotite and occasionally plagioclase. No quartz and no feldspar or feldspar content (<10%).
Olivine is the main basis for the classification of rock species. According to the content of olivine, the main rocks belong to pure Peridotite, Peridotite and pyroxenite. According to the properties of pyroxene, Peridotite and pyroxenite can be subdivided into species, such as single glow Peridotite, two glow Peridotite, Fang Hui Peridotite and olivine Dan Huihui stone, olives two pyroxenite, olives Fang Huihui stone, Dan Huihui stone, two diabase, and Fang Huihui rock. Sometimes amphibole is involved in the naming of rocks. The main mineral composition of amphibole is hornblende.

Shaanxi Shangnan Songshugou Moyu, demonstration name serpentinized pure Peridotite. The color is dark green, the main mineral composition is olivine and serpentine. It was developed in 1986, producing or processing plates or carving stones.
Peridotite, stone varieties have Sichuan mi Cangshan's Micang black. Micang black (No. 1) contains the following actual mineral composition: Olivine 30% ~ 95%, pyroxene 0% ~ 55%, basic plagioclase 0% ~ 30%.
Hui (stone) rock and stone materials such as Anhui Yuexi panther, Yunnan Huaping black, Hebei Yixian County G1136, etc. The name of the G1136 rock is perilla pyroxenite. The G1137 of Yixian County, Hebei is named "olive two pyroxene amphibolite". Its mineral composition is mainly amphibole, followed by pyroxene and olivine. One of the most important types of rock rock rock black gang Chinese pyroxene.
The so-called iron titanium Xia eclogite, aegirine nepheline - nephelinite is a genus of the class. Stone varieties such as Sichuan flying Mo-tse jade, in black green base, semi self shaped Lavender titanopyroxene, like flying purple flowers, decorative effect is excellent. In petrology, ultrabasic rocks are generally divided into four groups: Peridotite to bittern, Kimberley rock, carbonatite and neigasite nepheline. Among them, the bittern is Peridotite corresponding rock ejected.
The selective wear of mineral core will cause the change of its internal material composition, resulting in the depletion and enrichment of minerals, and the distortion of original grade and grade.

Color:
It is usually dark and dark.

Chemical property：
The content of SiO2 is low, and is rarely more than 45%. It is silicic acid unsaturated rock, A12O3 is low, Na20 and K2O content is very few, Mg and FeO are very high.

Experimental research and analysis:
Manufacture measurement
In order to standardize the comparability with other rocks, a flat surface is planed on the Peridotite sample so that it can be placed on the sample table in the center of the two photometer, adjust the horizontal position and height, then open the light source, rotate the polarizer in front of the light source to the desired angle, and each sample is A (690~76). 0nm) and B (760~1100nm) are measured at two wavelengths of no polarizer, 0 polarization, and 90 polarizations, respectively. The reflectance spectra of the 2 polarized space are measured, and the height angle of the incident light source is changed to determine the reflectance spectra at different height angles. Taking the 4 factors as incident angle, band and polarized light as variable factors, we study their influence on the reflection spectrum of Peridotite in 2 space.

Spectral analysis:
(a) reflection spectra of Peridotite in the general characteristics of the space are 2
Peridotite in the B (760~1100nm) band, without the polarizer, the light is 0 degrees in the azimuth angle and the incident angle is 50 degrees (calculated with the zenith angle of 0 degrees, and the azimuth angle of the incident ray is constant 0 degrees), the spectral curves of the Peridotite in the 2 space are obtained, in which the transverse coordinates indicate the square angle of the water, the change of the detection angle from 0 degrees ~360 degrees, the detection angle. The height angle changes from 0 degree ~60 degrees (0 degrees to the zenith angle), and the longitudinal coordinates are the reflected energy intensity values of the reflection spectrum (to simplify the figure, and to give out the curve of 0, 20 degrees). Figure 2 is a stereogram that corresponds to the spectral curve of the reflection (using the origin as the pole, using the reflection energy intensity as the polar diameter, to establish a polar coordinate system so that each direction in the 2 space corresponds to a reflection energy intensity value).
The reflection spectrum of Peridotite in there are obvious differences between the 2 are non Lambertian space, showing strong characteristics. The common value has a great relationship with the detection angle. For the detection angle of 0 degrees, 10 degrees and 20 degrees, the spectral characteristics do not change with the change of the azimuth angle. It is basically a straight line (rounding 0 degrees, 20 degrees curve is also the reason, theoretically, the 0 degree wave curve is a no wave line). Figure 3 is the plane relationship between the spectral curve and the azimuth angle of the 10 degree angle in Figure 1. The point in the figure is the observation value. The solid line is a circle with its mean 0.551mA. It can be seen that the fitting effect is very good.
However, when the detection angle is 30 ~60 degrees, the spectral curve peaks between 160 degrees and ~200 degrees. The fluctuation degree varies with the probe angle. The curves of 30 and 40 degrees have a weak peak, and the spectral curves of 50 degrees and 60 degrees have a strong peak. Figure 4 is the plane relation diagram of the detection angle 60 degree spectral curve and azimuth in Figure 1. It is not difficult to find that the right half part of the Y axis is a semicircle, while the left half part is extended. This indicates that when the detection angle is large, the mirror reflection effect of the ground surface is enhanced, and the original Lambert property of the object is destroyed.
From the spectral data analysis, the energy obtained by the detection angle of 0 degrees, 10 degrees and 20 degrees has no significant difference. The energy intensity obtained by 20 degrees is the largest, the mean value is 0.621mA, the 0 degree is 0.612mA, and the 10 degree is 0.551mA. Therefore, in Figure 2, their energy surfaces appear folds when the detection angle is 10 degrees. For the detection angle of 50 degrees and 60 degrees, the energy obtained in the area without the peak is significantly reduced, which is only equivalent to more than half of the former. Therefore, the overlook Figure 2, the energy surface at 50 degrees is completely covered by the energy surface with the detection angle of 40 degrees, and the energy surface of only 60 degrees is in the region of the present wave peak, and its energy surface is from the surface. A sharp stretch of the cover. Peridotite

(two) the relation between the reflection spectrum of Peridotite and the incident angle of light.
When the incident angle of the light source is 10 degrees, the angle curves are all straight, and there is no obvious peak phenomenon. It has a certain characteristic of the Lambert body, and the spectral curves of the detection angle of 30 and 40 degrees coincide almost. When the incident angle of light is 20 degrees, the spectral pattern is also shown in Figure 5. But when the incident angle of light is 30, 40, 50, and 60 degrees, the spectra show strong non Lambert properties, as shown in figures 6, 7 and 1. Moreover, when the detection angle is equal to the incident angle, the peak (polarization) phenomenon is most obvious. The change of incident angle has the strongest influence on the detection angle of 60 degree spectrum.
The above results show that the light source has little influence on the spatial characteristics of the spectral curve when incident at a small angle of incident (0 ~20 degrees), and shows a certain Lambert body characteristics at the same detection height angle. When the light source is incident at a large angle of 30 degrees (30 degrees), the spectral curve has a larger influence, showing the polarization of the opposite angle.
(three) the relationship between reflection spectrum and band of Peridotite.
Under the same conditions, the spectral curve of A band and the incident angle of light is 60 degrees. At this time, the phenomenon of peak (polarization) is also observed. The same is true for other large angles. This phenomenon shows that the peak (polarization) phenomenon of the reflection spectrum of Peridotite in the 2 space is a spatial spectral law inherent to the Peridotite (ground object), and has no significant relationship with the wavelength of the light. Although the waveform is similar, the intensity of reflected energy varies numerically. This shows that under the same detection angle, the reflection ability of Peridotite to the light of different wavelengths is different. It shows that the reflection spectral energy intensity of Peridotite in the 2 space is influenced by the wavelength of light.
(four) polarization state of Peridotite reflection spectrum.
The sun is a transverse wave, so the light is polarized. There are various reflector polarizers in nature, such as lakes, water surfaces, ice and snow, desert and clouds. Its characteristics are as follows: on the plane perpendicular to the reflected light, the energy distribution in each direction is uneven, and the polarization occurs, and most of them are elliptical. Only when the incident at the Brewster angle, the reflected light is linear polarized light. Is the polarization of light reflected after Peridotite? Secondly, if polarized light can be generated, then what is the rule of polarization in the reflection spectrum of Peridotite at different spatial locations? The authors measured the reflectance spectra of Peridotite without polarizing plates and polarizing plates, and measured at two perpendicular angles (0 degrees and 90 degrees).
Comparing the reflectance spectra of these 3 states, we can see that their waveform characteristics are not significantly different, but there are differences in spectral reflectance energy intensity. Taking the same point of space as an example (plane azimuth 170 degrees, vertical detection angle 60 degrees), the value is 1.908mA at the time of without polarization, and its value is 1.653mA under 90 degree of polarization, only 1.027mA under 0 degrees of polarization, and the values of three states measured by other space points are not the same. This fully confirms the polarization of the light after the Peridotite reflection, but in the plane perpendicular to the reflected light (wave direction), the electric vector distribution (oval) of the light can not be determined, because the polarization of 0 and 90 degrees does not really correspond to the long and short axis of the ellipse at this time.