A solar optical hyperspectral library of rare-earth-bearing minerals, rare-earth oxide powders, copper-bearing minerals and Apliki mine surface samples

Abstract. Mineral resource exploration and mining is an essential part of today's high-tech industry. Elements such as rare-earth elements (REEs) and copper are, therefore, in high demand. Modern exploration techniques from multiple platforms (e.g., spaceborne and airborne), to detect and map the spectral characteristics of the materials of interest, require spectral libraries as an essential reference. They include field and laboratory spectral information in combination with geochemical analyses for validation. Here, we present a collection of REE- and copper-related hyperspectral spectra with associated geochemical information. The libraries contain reflectance spectra from rare-earth element oxides, REE-bearing minerals, copper-bearing minerals and mine surface samples from the Apliki copper–gold–pyrite mine in the Republic of Cyprus. The samples were measured with the HySpex imaging spectrometers in the visible and near infrared (VNIR) and shortwave infrared (SWIR) range (400–2500 nm). The geochemical validation of each sample is provided with the reflectance spectra. The spectral libraries are openly available to assist future mineral mapping campaigns and laboratory spectroscopic analyses. The spectral libraries and corresponding geochemistry are published via GFZ Data Services with the following DOIs: https://doi.org/10.5880/GFZ.1.4.2019.004 (13 REE-bearing minerals and 16 oxide powders, Koerting et al., 2019a), https://doi.org/10.5880/GFZ.1.4.2019.003 (20 copper-bearing minerals, Koellner et al., 2019), and https://doi.org/10.5880/GFZ.1.4.2019.005 (37 copper-bearing surface material samples from the Apliki copper–gold–pyrite mine in Cyprus, Koerting et al., 2019b). All spectral libraries are united and comparable by the internally consistent method of hyperspectral data acquisition in the laboratory.

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A solar optical hyperspectral library of rare earth-bearing minerals, rare earth oxides, copper-bearing minerals and Apliki mine surface samples

10.5194/essd-2019-228 ◽

2019 ◽

Author(s):

Friederike Koerting ◽

Nicole Koellner ◽

Agnieszka Kuras ◽

Nina K. Boesche ◽

Christian Rogass ◽

...

Keyword(s):

Rare Earth ◽

Spectral Characteristics ◽

Short Wave ◽

High Tech ◽

Surface Samples ◽

Infra Red ◽

Copper Gold ◽

The Republic ◽

Republic Of Cyprus ◽

Spectral Libraries

Abstract. Mineral resource exploration and mining is an essential part of today’s high-tech industry. Elements such as rare earth elements (REE) and copper are, therefore, in high demand. Modern exploration techniques from multiple platforms (e.g. space- and airborne), to detect and map the spectral characteristics of the materials of interest, require spectral libraries as an essential reference. They include field and laboratory spectral information in combination with geochemical analyses for validation. Here, we present an extensive collection of REE- and copper-related hyperspectral spectra with associated geochemical information. The libraries contain spectra from rare earth element oxides, REE-bearing minerals, copper-bearing minerals and mine surface samples from the Apliki copper-gold-pyrite-mine in the Republic of Cyprus. The samples were measured with the HySpex imaging spectrometers in the visible near infra-red (VNIR) and short wave infra-red (SWIR) range (400–2500 nm). The geochemical validation of each sample is provided with the spectra. The spectral library is openly available to assist future mineral mapping campaigns and laboratory spectroscopic analyses. The spectral libraries and corresponding geochemistry are published via GFZ Data Services with the following DOIs: https://doi.org/10.5880/GFZ.1.4.2019.004 (REE elements, Koerting et al., 2019a), https://doi.org/10.5880/GFZ.1.4.2019.003 (Copper bearing minerals. Koellner et al., 2019), and https://doi.org/10.5880/GFZ.1.4.2019.005 (copper bearing minerals from the Apliki copper-gold-pyrite mine in Cyprus, Koerting et al., 2019b).

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Soil Organic Carbon Estimation using VIS–NIR–SWIR Spectroscopy: The Effect of Multiple Sensors and Scanning Conditions

10.31219/osf.io/z7htf ◽

2020 ◽

Author(s):

Asa Gholizadeh ◽

Carsten Neumann ◽

Sabine Chabrillat ◽

Bas van Wesemael ◽

Fabio Castaldi ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Near Infrared ◽

Prediction Models ◽

Soil Samples ◽

Reflectance Spectra ◽

Multiple Sensors ◽

Laboratory Spectrum ◽

Spectral Libraries ◽

Shortwave Infrared

Visible–near infrared–shortwave infrared (VIS–NIR–SWIR) spectroscopy is being increasingly used for soil organic carbon (SOC) assessment. Common practice consists of scanning soil samples using a single spectrometer. Considerations have rarely been documented of the effects of using multiple instruments and scanning conditions on SOC model calibration that occur when merging soil spectral libraries (SSLs), particularly in soils with low SOC concentration and using both field spectroradiometers and laboratory fixed spectrometers. To address this gap, we scanned 143 low-SOC-content soil samples using three spectrometers (ASD FieldSpec 3, ASD FieldSpec 4, and FOSS XDS) and four setup features - FOSS, contact probe (CP), dark-box (DB), and open laboratory (LAB) - at three laboratories. The application of an internal soil standard (ISS) to align one laboratory spectrum with another for spectral correction and spectral merging of various SSLs was examined. SOC models were developed using i) data from each single spectrometer – single laboratory separately and ii) merged data from multiple spectrometers – different laboratories, applying the 1st derivatives of spectra and random forest (RF) regression. The results indicate that the spectral shape and position obtained from all spectrometers and setups did not show any noticeable differences, though spectra based on FOSS setup, particularly on low-SOC samples, demonstrated the highest absolute derivative values regardless of ISS application. The derivative ISS-corrected spectra showed less variation among different spectrometers compared to their uncorrected reflectance spectra. All single spectrometer models predicted SOC reasonably well. However, the spectra acquired by the FOSS setup predicted SOC more accurately (R2 = 0.77 and SD = 0.04) than the spectra acquired by the other setups. The models derived from merged uncorrected reflectance spectra yielded poor results (R2 = 0.48 and SD = 0.10); nevertheless, assessment of SOC using the 1st derivative ISS-corrected merged SSLs considerably improved the prediction accuracy (R2 = 0.70 and SD = 0.06). Hence, the derivative spectra coupled with the ISS correction improved the accuracy of SOC prediction models obtained from merged soil spectra collected in different environments using different instruments. We therefore recommend application of the ISS spectral alignment method linked to the 1st derivative approach to enhance the compilation of SSLs at the regional and global scales for SOC assessment.

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Spektroskopi Reflektansi Sampel Tanah dan Batuan yang Mengandung Mineral Pembawa Unsur Tanah Jarang dan Radioaktif

EKSPLORIUM ◽

10.17146/eksplorium.2019.40.2.5644 ◽

2019 ◽

Vol 40 (2) ◽

pp. 89

Author(s):

Arie Naftali Hawu Hede ◽

Muhammad Anugrah Firdaus ◽

Yogi La Ode Prianata ◽

Mohamad Nur Heriawan ◽

Syafrizal Syafrizal ◽

...

Keyword(s):

Remote Sensing ◽

Rare Earth ◽

Optical Sensors ◽

Near Infrared ◽

Spectral Characteristics ◽

Infrared Range ◽

Basic Principles ◽

Spectral Signatures ◽

Shortwave Infrared ◽

Remote Sensing Methods

ABSTRAKSpektroskopi reflektansi merupakan salah satu metode nondestruktif untuk identifikasi mineral dan sebagai dasar dalam analisis pengindraan jauh (indraja) sensor optik. Penelitian ini bertujuan melakukan kajian penerapan spektroskopi reflektansi pada panjang gelombang 350–2.500 nm untuk sampel tanah dan batuan pembawa unsur tanah jarang (rare earth element-REE) dan radioaktif. Sampel diambil dari beberapa lokasi di Bangka Selatan dan Mamuju yang sebelumnya telah diidentifikasi memiliki potensi REE dan unsur radioaktif. Kurva reflektansi hasil analisis sampel dari Bangka Selatan menunjukan adanya kenampakan absorpsi yang menjadi karakteristik untuk kehadiran REE, dalam bentuk mineral monasit, zirkon, dan xenotime khususnya pada sampel yang berasal dari material tailing dan konsentrat bijih timah. Panjang gelombang yang menjadi kunci khususnya berada pada rentang visible-near infrared (VNIR; 400–1.300 nm). Sedangkan untuk sampel yang berasal dari Mamuju, yang merupakan daerah prospeksi mineral radioaktif, karakteristik spektral memperlihatkan beberapa panjang gelombang kunci terutama pada rentang shortwave infrared (1.300–2.500 nm). Hasil interpretasi menunjukkan mineral mayor berupa mineral lempung, sulfat, spesies NH4, dan mineral yang mengandung Al-OH lainnya, sedangkan untuk beberapa sampel pada panjang gelombang VNIR diidentifikasi mengandung mineral besi oksida/hidroksida. Hasil penelitian ini diharapkan dapat berguna untuk pemetaan eksplorasi REE dan radioaktif dengan menggunakan metode indraja.ABSTRACTReflectance spectroscopy is one of the nondestructive methods of mineral identification and is one of the basic principles in the remote sensing analysis using optical sensors. This research aimed at applying reflectance spectroscopy at 350–2,500 nm wavelength range for samples containing rare earth elements (REE) and radioactive minerals. Samples were taken from several locations in South Bangka and Mamuju that had previously been identified as potential location of REE and radioactive-bearing minerals. Reflectance data shows that there are absorption characteristics for REE-bearing minerals; monazite, zircon, and xenotime minerals especially from tailings and tin ore concentrate for the samples from South Bangka. The key wavelengths are specifically in the visible-near infrared range (VNIR; 400–1300 nm). For the samples from Mamuju, which is known as radioactive mineral prospecting areas, spectral characteristics provide information that there are spectral signatures in the shortwave infrared range (1,300–2,500 nm). The results of major mineral interpretations include clay minerals, sulfates, NH4 species, and other minerals containing Al-OH. However, some samples at the VNIR wavelength identified as iron oxide/hydroxide minerals. It is hoped that these results can be useful for REE and radioactive exploration mapping using remote sensing methods.

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DIFFERENT STATISTICAL METHODS FOR THE DISCRIMINATION OF TROPICAL MANGROVE SPECIES USING IN-SITU HYPERSPECTRAL DATA

Journal of Hyperspectral Remote Sensing ◽

10.29150/jhrs.v9.2.p49-67 ◽

2019 ◽

Vol 9 (2) ◽

pp. 49

Author(s):

Tanumi Kumar ◽

Dibyendu Dutta ◽

Diya Chatterjee ◽

K Chandrasekar ◽

Goru Srinivasa Rao ◽

...

Keyword(s):

Near Infrared ◽

Infrared Region ◽

Hyperspectral Data ◽

Feature Reduction ◽

Reflectance Spectra ◽

Stepwise Discriminant Analysis ◽

Species Discrimination ◽

Mangrove Species ◽

Domain Specific ◽

Continuum Removal

The study highlights the hyperspectral characteristics of canopies of 14 tropical mangrove species, belonging to nine families found in the tidal forests of the Indian Sundarbans. Hyperspectral observations were recorded using a field spectroradiometer, pre-processed and subjected to derivative analysis and continuum removal. Mann-Whitney U tests were applied on the spectral data in four spectral forms: (i) Reflectance Spectra (ii) First Derivative, (iii) Second Derivative and (iv) Continuum Removal Reflectance Spectra. Factor analysis was applied in each of the spectral forms for feature reduction and identification of the important wavelengths for species discrimination. Stepwise discriminant analysis was used on the feature reduced reflectance spectra to obtain optimal bands for computation of Jeffries–Matusita distance. The Mann-Whitney U test could be satisfactorily used for determining the significant (separable) bands for discriminating the species. In general, the red region, red edge domain, specific near infrared bands (including 759, 919, 934, 940, 948, 1152, 1156, 1159 and 1212 nm) and shortwave infrared region (1503–1766 nm) played major roles in spectral separability. Overall, hyperspectral data showed potential for discriminating between mangrove canopies of different species and the results of the study also indicated the usefulness of the applied statistical tools for discrimination.

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Diffuse-Reflectance Spectra of Rare-Earth Oxides

Applied Spectroscopy ◽

10.1366/000370267774385173 ◽

1967 ◽

Vol 21 (3) ◽

pp. 167-171 ◽

Cited By ~ 34

Author(s):

William B. White

Keyword(s):

Rare Earth ◽

Diffuse Reflectance ◽

Near Infrared ◽

Diffuse Reflectance Spectroscopy ◽

Rare Earth Oxides ◽

Rare Earth Ions ◽

Reflectance Spectra ◽

Solid Materials ◽

Diffuse Reflectance Spectra ◽

Structural Types

Diffuse-reflectance spectra are reported for 11 rare-earth oxides of various structural types over the spectral range of 225–2700 mμ. These spectra, particularly in the near infrared, permit the use of diffuse-reflectance spectroscopy to identify rare-earth ions in solid materials.

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Mapping Rare Earth Minerals with Near-Infrared Reflectance Spectra

10.1190/segj102011-001.102 ◽

2011 ◽

Author(s):

Shuichi Miyatake ◽

Taro Yajima ◽

Yuu Kawakami ◽

Shinsuke Kodama ◽

Hirohisa Kamijo ◽

...

Keyword(s):

Rare Earth ◽

Near Infrared ◽

Reflectance Spectra ◽

Infrared Reflectance ◽

Near Infrared Reflectance ◽

Rare Earth Minerals

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Analysis of spectroscopic diffuse reflectance plots for different skin conditions

Spectroscopy An International Journal ◽

10.1155/2010/791473 ◽

2010 ◽

Vol 24 (5) ◽

pp. 467-481 ◽

Cited By ~ 4

Author(s):

Shanthi Prince ◽

S. Malarvizhi

Keyword(s):

Diffuse Reflectance ◽

Near Infrared ◽

Skin Diseases ◽

Diffuse Reflectance Spectroscopy ◽

Spectral Characteristics ◽

Reflectance Spectra ◽

Diffuse Reflectance Spectra ◽

Spectral Curves ◽

Skin Conditions

Optical means of characterizing tissues have gained importance due to its noninvasive nature. Spectral characteristics of the components provide useful information to identify the components, because different chromophores have different spectroscopic responses to electromagnetic waves of a certain energy band. The purpose of this study is to determine whether visible/near-infrared diffuse reflectance spectroscopy can be used to non-invasively characterize skin diseasesin vivo.An optical fiber spectrometer is set up for obtaining diffuse reflectance spectra. The method involves exposure of skin surface to white light produced by an incandescent source. The back scattered photons emerging from various layers of tissue are detected by spectrometer resulting in diffuse reflectance spectra.For the present study different skin conditions like – warts, vitiligo, thrombus (due to injury) and angioma are chosen. The spectral data obtained from the scan are plotted and compared. More or less, the shapes of the spectral curves for various skin conditions resemble. In order to characterize and differentiate different diseased state spectral analysis based on Ratio analysis, Student'st-tests and difference plot are carried out.Based on the analysis the relative spectral intensity changes are quantified and the spectral shape changes are enhanced and more easily visualized on the spectral curves, thus assisting in differentiating the normal tissue from the one affected by disease.

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China and the Geopolitics of Rare Earths

10.1093/oso/9780190670931.001.0001 ◽

2017 ◽

Cited By ~ 3

Author(s):

Sophia Kalantzakos

Keyword(s):

Rare Earth ◽

Rare Earths ◽

Resource Competition ◽

Renewable Energy Sources ◽

High Tech ◽

Trade Dispute ◽

Policy Responses ◽

Economic Statecraft ◽

The Rare Earth

In 2010, because of a geopolitical incident between China and Japan, seventeen elements of the periodic table known as rare earths became notorious overnight. An “unofficial” and temporary embargo of rare-earth shipments to Japan alerted the world to China’s near monopoly position on the production and export of these indispensable elements for high-tech, defense, and renewable energy sources. A few months before the geopolitical confrontation, China had chosen to substantially cut export quotas of rare earths. Both events sent shockwaves across the markets, and rare-earth prices skyrocketed, prompting reactions from industrial nations and industry itself. The rare-earth crisis is not a simple trade dispute, however. It also raises questions about China’s use of economic statecraft and the impacts of growing resource competition. A detailed and nuanced examination of the rare-earth crisis provides a significant and distinctive case study of resource competition and its spill-over geopolitical effects. It sheds light on the formulation, deployment, longevity, effectiveness, and, perhaps, shortsightedness of policy responses by other industrial nations, while also providing an example of how China might choose to employ instruments of economic statecraft in its rise to superpower status.

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Activatable Rare Earth Near-Infrared-II Fluorescence Ratiometric Nanoprobes

Nano Letters ◽

10.1021/acs.nanolett.1c01962 ◽

2021 ◽

Author(s):

Ziqiang Sun ◽

Haoying Huang ◽

Rong Zhang ◽

Xiaohu Yang ◽

Hongchao Yang ◽

...

Keyword(s):

Rare Earth ◽

Near Infrared

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Atmospheric Compensation of PRISMA Data by Means of a Learning Based Approach

Remote Sensing ◽

10.3390/rs13152967 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2967

Author(s):

Nicola Acito ◽

Marco Diani ◽

Gregorio Procissi ◽

Giovanni Corsini

Keyword(s):

Spectral Range ◽

Near Infrared ◽

Random Noise ◽

Synthetic Data ◽

Regression Function ◽

Short Wave ◽

Hyperspectral Data ◽

Electromagnetic Spectrum ◽

Great Opportunity ◽

Atmospheric Compensation

Atmospheric compensation (AC) allows the retrieval of the reflectance from the measured at-sensor radiance and is a fundamental and critical task for the quantitative exploitation of hyperspectral data. Recently, a learning-based (LB) approach, named LBAC, has been proposed for the AC of airborne hyperspectral data in the visible and near-infrared (VNIR) spectral range. LBAC makes use of a parametric regression function whose parameters are learned by a strategy based on synthetic data that accounts for (1) a physics-based model for the radiative transfer, (2) the variability of the surface reflectance spectra, and (3) the effects of random noise and spectral miscalibration errors. In this work we extend LBAC with respect to two different aspects: (1) the platform for data acquisition and (2) the spectral range covered by the sensor. Particularly, we propose the extension of LBAC to spaceborne hyperspectral sensors operating in the VNIR and short-wave infrared (SWIR) portion of the electromagnetic spectrum. We specifically refer to the sensor of the PRISMA (PRecursore IperSpettrale della Missione Applicativa) mission, and the recent Earth Observation mission of the Italian Space Agency that offers a great opportunity to improve the knowledge on the scientific and commercial applications of spaceborne hyperspectral data. In addition, we introduce a curve fitting-based procedure for the estimation of column water vapor content of the atmosphere that directly exploits the reflectance data provided by LBAC. Results obtained on four different PRISMA hyperspectral images are presented and discussed.

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