CN114965343A - Method for analyzing olivine components based on thermal infrared spectroscopy technology and application - Google Patents

Abstract

The invention discloses a method and application for analyzing olivine components based on thermal infrared spectroscopy technology, and solves the complicated, time-consuming and laborious operations that exist when the olivine components are analyzed by on-site sampling combined with the electronic probe technology in the laboratory. And the problem of high application cost. The main implementation steps of the method are: 1. Extract multiple sets of olivine sample data from the open source spectral database, and obtain the wavelength value corresponding to the main absorption valley of the olivine in the thermal infrared band, the FeO mass percentage content and the MgO mass percentage in the olivine respectively. The linear relationship between the contents; 2. Input the two linear relationships into the thermal infrared spectrometer respectively; 3. Use the thermal infrared spectrometer to detect the olivine sample to be analyzed, and obtain the wavelength value of the main absorption valley of the olivine sample to be analyzed. 4. Calculate the Fe/Mg molar ratio of the olivine sample to be analyzed.

Description

Method and application of olivine composition analysis based on thermal infrared spectroscopy

technical field

The invention belongs to the technical field of mineral chemical composition identification, in particular to a method and application for analyzing olivine composition based on thermal infrared spectroscopy technology.

Background technique

Olivine, a natural gemstone, has a chemical formula of (Mg _x , Fe _2-x )SiO ₄ . Its parent rock is the most important rock-forming mineral in the mantle, a silicate of magnesium and iron. Its main components are iron, magnesium, silicon, and can also contain elements such as manganese, nickel, and cobalt. The crystals are granular, and are dispersed particles or granular aggregates in rocks. Belongs to island silicate. Olivine can be altered to form serpentine or magnesite, which can be used as refractory materials.

The composition of olivine is mainly composed of two end-member components Mg ₂ [SiO ₄ ] and Fe ₂ [SiO ₄ ]. It is a completely isomorphic mixed crystal, and sometimes it can also contain more Ca ²⁺ to form a complex crystal. The complete isomorphic series of salt CaMg[SiO ₄ ]-CaFe[SiO ₄ ] and the above-mentioned complete isomorphic series of forsterite-fayalite rarely have isomorphism.

For a long time, olivine, as the main constituent mineral of mantle peridotite and the earliest crystallized mineral of magma, has been the main research object for exploring magmatic process, mantle thermal state and mantle endmember composition. Effective information on partial melting of the mantle and early crystallization of magma, and mantle metasomatism.

When using olivine for geological research, the traditional practice is to sample the olivine in the area to be studied and bring the olivine sample back to the laboratory where the olivine sample is ground into powder and then compositionally determined using electron probe technology. analyze.

The disadvantages of this method are: firstly, the experimental operation process is complicated and time-consuming; secondly, the application cost of electronic probe technology is high.

SUMMARY OF THE INVENTION

In order to solve the problems of complicated, time-consuming and laborious operation and high application cost when analyzing olivine components by on-site sampling combined with electronic probe technology in the laboratory.

A first aspect of the present invention provides a method for analyzing olivine components based on thermal infrared spectroscopy, and the implementation steps of the method are as follows:

Step 1: Extract multiple sets of olivine sample data from the open source spectral database, and obtain the linearity between the wavelength value corresponding to the main absorption valley of olivine in the thermal infrared band and the mass percentage content of FeO in olivine from the multiple sets of olivine sample data At the same time, the linear relationship between the wavelength value corresponding to the main absorption valley of olivine in the thermal infrared band and the mass percentage content of MgO in olivine was obtained from multiple sets of olivine sample data;

Step 2: The linear relationship between the wavelength value corresponding to the main absorption valley of olivine and the mass percentage content of FeO in olivine, and the wavelength value corresponding to the main absorption valley of olivine and the mass percentage content of MgO in olivine The linear relationship is respectively input into the thermal infrared spectrometer;

Step 3: use the thermal infrared spectrometer of step 2 to detect the olivine sample to be analyzed, and obtain the mass percentage content of MgO and FeO in the olivine sample to be analyzed that the wavelength value of the main absorption valley of the olivine sample to be analyzed is within 10-11 μm;

Step 4: The thermal infrared spectrometer uses the mass percentage content of MgO and FeO in the olivine sample to be analyzed obtained in step 3 to calculate the Fe/Mg molar ratio of the olivine sample to be analyzed.

By storing the linear relationship between the wavelength value corresponding to the olivine in the main absorption valley and the mass percentage content of FeO and MgO in the olivine, the present invention can calculate the Fe/Mg molar ratio of the olivine sample to be analyzed in real time, thereby rapidly Compared with the existing detection methods, the analysis of olivine components is realized, and the detection efficiency is greatly improved, and the sample itself will not be damaged.

Specifically, in the above step 1, the linear relationship between the wavelength value corresponding to the main absorption valley of the olivine in the thermal infrared band and the FeO mass percentage content in the olivine is:

wt ^FeO = 120.5512*λ-1232.0665;

Among them, wt ^FeO is the mass percentage content of FeO, λ is the wavelength value corresponding to the main absorption valley of olivine in the thermal infrared band, and the unit is micrometer.

Specifically, in the step 1 described in the above step 1, the linear relationship between the wavelength value corresponding to the main absorption valley of the olivine in the thermal infrared band and the MgO mass percentage content in the olivine is:

^wtMgO =-101.1970*λ+1091.9951;

Among them, wt ^FeO is the mass percentage content of MgO, λ is the wavelength value corresponding to the main absorption valley of olivine in the thermal infrared band, and the unit is micrometer.

Specifically, the specific calculation formula of the Fe/Mg molar ratio of the olivine sample in the above step 4 is: mol(Fe/Mg)=wt ^FeO /wt ^MgO *40.3044/71.8444;

Among them, 40.3044 is the molecular weight of MgO, and 71.8444 is the molecular weight of FeO.

Specifically, the specific process of obtaining the linear relationship between the wavelength value corresponding to the main absorption valley of the olivine in the thermal infrared band and the FeO mass percentage content in the olivine from the multiple groups of olivine sample data in the above step 1 is:

Step S1: screen out a plurality of olivine sample data with both thermal infrared spectral data and mineral electron probe analysis data in the open source spectral database;

Step S2: extracting the wavelength value corresponding to the main absorption valley of the thermal infrared band from the thermal infrared spectral data corresponding to the multiple olivine sample data respectively;

Step S3: extracting the FeO mass percentage content in the olivine sample from the mineral electron probe analysis data corresponding to the data of the multiple olivine samples respectively;

Step S4: Perform linear regression fitting on the wavelength value and the mass percentage content extracted in steps S2 and S3 to obtain a linear relationship between the wavelength value and the mass percentage content.

Specifically, the specific process of obtaining the linear relationship between the wavelength value corresponding to the main absorption valley of the olivine in the thermal infrared band and the MgO mass percentage content in the olivine from the multiple groups of olivine sample data in the above step 1 is:

Step S1: screen out a plurality of olivine sample data with both thermal infrared spectral data and mineral electron probe analysis data in the open source spectral database;

Step S2: extracting the wavelength value corresponding to the main absorption valley of the thermal infrared band from the thermal infrared spectral data corresponding to the multiple olivine sample data respectively;

Step S3: extracting the MgO mass percentage content in the olivine sample from the mineral electron probe analysis data corresponding to the data of the multiple olivine samples respectively;

Step S4: Perform linear regression fitting on the wavelength value and the mass percentage content extracted in steps S2 and S3 to obtain a linear relationship between the wavelength value and the mass percentage content.

Specifically, the above-mentioned open source spectral database is the NASAECOSTRESS spectral library or the USGS spectral library.

Specifically, the spectral range of the thermal infrared spectrometer in the above-mentioned step 3 includes 8-12 μm, and the spectral resolution is better than 25 nm.

The second aspect of the present invention provides an application of the method for analyzing the above olivine components in geological research.

The second aspect of the present invention provides an application of the method for analyzing the above-mentioned olivine components in jewelry identification.

The beneficial effects of the present invention are:

1. The present invention skillfully utilizes the linear relationship between the wavelength value corresponding to the main absorption valley of olivine between 10-11 μm and the mass percentage content of MgO and FeO in olivine. The Fe/Mg ratio of olivine is measured by the technology, and compared with the method of traditional field sampling combined with the electronic probe technology in the laboratory, the method of the present invention can quickly, accurately and economically determine Fe of olivine in a short time on the geological site. The molar ratio of /Mg has positive application value for geological research, geochemical tracing, and jewelry identification.

2. The present invention skillfully utilizes thermal infrared spectrum measurement technology to measure the Fe/Mg ratio of olivine, and does not need to sample the olivine and grind it into powder for jewelry identification, thereby avoiding unnecessary waste of jewelry.

Description of drawings

Figure 1 shows 15 olivine thermal infrared spectra of the USGS spectral library used in the examples.

Fig. 2 is the 15 olivine thermal infrared spectrograms of the NASAECOSTRESS spectral library used in the embodiment.

3 is a linear relationship between the MgO content and the wavelength of the main absorption valley in the 10-11um interval of olivine in the embodiment.

Figure 4 is a linear relationship between FeO content and the wavelength of the main absorption valley in the olivine 10-11um interval in the embodiment.

Detailed ways

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the invention unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification.

In all examples shown and discussed herein, any specific values should be construed as illustrative only and not limiting. Accordingly, other instances of the exemplary embodiment may have different values.

As the main rock-forming mineral, olivine is widely used in geology. In industry, magnesium-rich olivine can be used as a refractory due to its high melting point. Large-grained, high-clarity peridot can be used as a gemstone material.

Olivine can undergo phase transformation under high pressure conditions to form wadsleyite (β-olivine) with a spinel-like structure and Ringwoodite (γ-olivine) with a spinel structure, which can be used as Indicator minerals for UHP metamorphism. The study of the phase transition process of olivine is of great significance for understanding the origin of the mantle discontinuity, the material composition and evolution of the entire mantle, mantle convection, and deep earthquakes in the subducting slab. At the same time, as a mantle rock capture body, the study of olivine is also a major way to understand the composition of mantle materials. As one of the main constituent minerals of stony meteorites, studying the characteristics of olivine can also indicate the origin of similar mantle materials on other planets in the universe.

The present embodiment provides a method for analyzing olivine components based on thermal infrared spectroscopy, and its main implementation process is as follows:

1. Select a thermal infrared spectrometer with a spectral range of 8-12μm and a spectral resolution better than 25nm;

2. Obtain the linear relationship between the wavelength value corresponding to the main absorption valley of olivine in the thermal infrared band and the mass percentage content of MgO in olivine, and the wavelength value corresponding to the main absorption valley of olivine and the mass percentage content of FeO in olivine. the linear relationship between;

In order to ensure the reliability and accuracy of the obtained linear relationship data, two open source spectral databases are used in this embodiment, namely: USGS spectral library and NASA's ECOSTRESSspectrallibrary spectral library; the reason for selecting the main absorption valley to obtain the linear relationship is that : The above two spectral libraries provide reflectance measurement data. The peaks are easily affected by external factors such as light, and are not the stable identification features of minerals. The valley-shaped features of the spectrum can better reflect the intrinsic absorption characteristics of minerals. ;

The specific process of obtaining a linear relationship is as follows:

A total of 15 olivine mineral samples with spectra measured by Nicolet and electron probe analysis data were screened from the USGS spectral library, and their main absorption valley wavelengths λ in the spectral range of 10-11 μm were read (Fig. 1) and MgO, FeO mass percentage content (Table 1);

From NASA's ECOSTRESSspectrallibrary spectral library, a total of 15 olivine mineral samples with measurement type "Bidirectionalreflectance" and electron probe analysis data were screened, and their main absorption valley wavelengths λ in the 10-11μm spectral range were read (Fig. 2) and its MgO, FeO weight percentage content (Table 2).

Table 1

Table 2

Regressing the FeO content and MgO content in the above table with the wavelength of the main absorption valley respectively (usually using the least squares method), the strong and significant linear relationship between the content of olivine MgO and FeO and the wavelength of the main absorption valley in the 10-11um interval can be obtained. See Figures 3 and 4;

wt ^MgO = -101.1970*λ+1091.9951; (1)

Among them, wt ^FeO is the mass percentage content of MgO, λ is the wavelength value corresponding to the main absorption valley of olivine in the thermal infrared band, and the unit is micron;

wt ^FeO = 120.5512*λ-1232.0665; (2)

Among them, wt ^FeO is the mass percentage content of FeO, λ is the wavelength value corresponding to the main absorption valley of olivine in the thermal infrared band, and the unit is micron;

3. Input the linear relationship formulas (1) and (2) obtained above into the thermal infrared spectrometer prepared in advance, use the thermal infrared spectrometer to collect the thermal infrared spectrum of the olivine sample to be analyzed, and extract its 10-11um range The wavelength of the main absorption valley, using the linear relationship formulas (1) and (2), to calculate the mass percentage content of FeO and MgO in the olivine sample to be analyzed; 4. Using the obtained mass percentage content of FeO and MgO in the olivine sample to be analyzed , calculate the Fe/Mg molar ratio of the olivine sample to be analyzed;

5. Since the chemical formula of olivine is (Mg _x , Fe _2-x )SiO ₄ , where X is to be determined, when the Fe/Mg molar ratio of the olivine sample to be analyzed is obtained, it is equivalent to the obtained olivine to be analyzed. Chemical composition of stone samples.

When the above analysis methods are applied to geological exploration, a portable thermal infrared spectrometer can be used to quickly obtain the composition of olivine in multiple different areas at the exploration site, without the need to bring the site olivine back to the laboratory. Efficiency is improved.

When the above analysis method is applied to jewelry identification, the composition of the olivine can be obtained only by using the thermal infrared spectrometer to detect the olivine. Compared with the existing method, in addition to the high detection efficiency, it does not need to cause any damage to the olivine itself. destroy.

Claims (10)

1. A method for analyzing the components of olivine based on thermal infrared spectroscopy is characterized by comprising the following steps:

step 1: extracting a plurality of groups of olivine sample data from the open-source spectrum database, acquiring a linear relation between a wavelength value corresponding to the main absorption valley of the olivine in the thermal infrared band and the mass percentage content of FeO in the olivine from the plurality of groups of olivine sample data, and acquiring a linear relation between a wavelength value corresponding to the main absorption valley of the olivine in the thermal infrared band and the mass percentage content of MgO in the olivine from the plurality of groups of olivine sample data;

step 2: respectively inputting the linear relation between the wavelength value corresponding to the olivine in the main absorption valley and the mass percentage content of FeO in the olivine, and the linear relation between the wavelength value corresponding to the olivine in the main absorption valley and the mass percentage content of MgO in the olivine into a thermal infrared spectrometer;

and step 3: detecting the olivine sample to be analyzed by adopting the thermal infrared spectrometer in the step 2, and respectively obtaining the mass percentage contents of MgO and FeO in the olivine sample to be analyzed, wherein the main absorption valley wavelength value of the olivine sample to be analyzed is within 10-11 mu m;

and 4, step 4: and 3, calculating the Fe/Mg molar ratio of the olivine sample to be analyzed according to the mass percentage content of MgO and FeO in the olivine sample to be analyzed, which is obtained in the step 3.

2. The method for the analysis of olivine components according to claim 1, based on thermal infrared spectroscopy, characterized in that: in the step 1, the linear relation between the corresponding wavelength value of the olivine in the main absorption valley of the thermal infrared band and the FeO content in the olivine by mass percentage is as follows:

wtFeO=120.5512*λ-1232.0665；

wherein wtFeO is the mass percentage content of FeO, and lambda is the wavelength value corresponding to the main absorption valley of the olivine in the thermal infrared band, and the unit is micrometer.

3. The method for the analysis of olivine components according to claim 2, characterized in that it comprises: in the step 1, the linear relation between the corresponding wavelength value of the main absorption valley of the olivine in the thermal infrared band in the step 1 and the MgO mass percentage content in the olivine is as follows:

wtMgO=-101.1970*λ+1091.9951；

wherein wtFeO is the mass percentage content of MgO, and lambda is the wavelength value corresponding to the main absorption valley of the olivine in the thermal infrared band, and the unit is micrometer.

4. A method for the analysis of olivine constituents based on thermal infrared spectroscopy techniques according to claim 3, characterized in that: the specific calculation formula of the Fe/Mg molar ratio of the olivine sample in the step 4 is as follows:

mol(Fe/Mg)=wtFeO/wtMgO*40.3044/71.8444；

wherein 40.3044 is the MgO molecular weight and 71.8444 is the FeO molecular weight.

5. A method for the analysis of the olivine composition according to any of claims 1 to 4, based on thermal infrared spectroscopy, characterized in that: the specific process of acquiring the linear relation between the wavelength value corresponding to the main absorption valley of the olivine in the thermal infrared band and the mass percentage content of FeO in the olivine from the multiple sets of olivine sample data in the step 1 is as follows:

step S1: screening a plurality of olivine sample data which simultaneously have thermal infrared spectrum data and mineral electronic probe analysis data from an open source spectrum database;

step S2: extracting wavelength values corresponding to main absorption valleys of thermal infrared bands from thermal infrared spectrum data respectively corresponding to a plurality of olivine sample data;

step S3: extracting the mass percentage content of FeO in the olivine sample from the mineral electronic probe analysis data respectively corresponding to the plurality of olivine sample data;

step S4: linear regression fitting is performed on the wavelength value and the mass percentage content extracted in step S2 and step S3 to obtain a linear relationship between the wavelength value and the mass percentage content.

6. A method for the analysis of the olivine composition according to any of claims 1 to 4, based on thermal infrared spectroscopy, characterized in that:

the specific process of acquiring the linear relation between the wavelength value corresponding to the main absorption valley of the olivine in the thermal infrared band and the MgO mass percentage content in the olivine from the multiple sets of olivine sample data in the step 1 is as follows:

step S1: screening a plurality of olivine sample data which simultaneously have thermal infrared spectrum data and mineral electronic probe analysis data in an open source spectrum database;

step S2: extracting wavelength values corresponding to main absorption valleys of thermal infrared bands from thermal infrared spectrum data respectively corresponding to a plurality of olivine sample data;

step S3: extracting the MgO mass percentage content in the olivine sample from the mineral electronic probe analysis data respectively corresponding to the plurality of olivine sample data;

step S4: linear regression fitting is performed on the wavelength value and the mass percentage content extracted in step S2 and step S3 to obtain a linear relationship between the wavelength value and the mass percentage content.

7. The method for the analysis of olivine constituents based on thermal infrared spectroscopy according to claim 1, wherein: the open source spectrum database is a NASAECOSTRES spectrum database or a USGS spectrum database.

8. The method for the analysis of olivine components according to claim 1, based on thermal infrared spectroscopy, characterized in that: the spectral range of the thermal infrared spectrometer in the step 3 comprises 8-12 μm, and the spectral resolution is better than 25 nm.

9. Use of the method for the analysis of olivine components according to claim 1 based on thermal infrared spectroscopy for geological research.

10. Use of the method for the analysis of olivine components according to claim 1 based on thermal infrared spectroscopy for the identification of jewelry.

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