The metallic reflectance can be related to the conductivity by the Hagens-Ruben equation (Equation \ref{5}), where ν is the light frequency, ε 0 is the vacuum permitivity (8.85 x 10-12 F/m), and σ is the conductivity. Other - NASA Technical Note (TN) Authors. We use cookies to help provide and enhance our service and tailor content and ads. Author links open overlay panel Olli Haavisto Jani Kaartinen. Hyperspectral remote sensing allows sampling at high temporal resolutions as well as rapid and non-destructive characterization of a wide range of mineralization, enabling identification of element content through spectral features. https://doi.org/10.1016/j.gexplo.2019.05.002. Although the ND-type index has a few limitations, it is a useful, simple, and robust indicator for determining Cu at high concentrations. Its relative reflectivity is much greater than surrounding surfaces. 4. Download : Download high-res image (502KB) Download : Download full-size image; Fig. Reflectance and conductivity. 19690022517 . The highest R 2, RMSE, and RMSE% values are given for each type of index. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. Data mining of the best spectral indices for geochemical anomalies of copper: A study in the northwestern Junggar region, Xinjiang. RESOURCES Metal Reflectivity Chart With metals, it is often desired to have a reflective surface-not necessarily blindingly bright but one that catches the eye. Soil samples were collected from an abandoned mine area, and the chemical analysis revealed extremely high contamination amount of copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), and lead (Pb). To investigate variations in rock Cu content and changes in spectral reflectance Cu content, To identify the best index for predicting Cu content, To examine the relationship between spectral indices and measured Cu content. Bowman, R. L. (NASA Lewis Research Center Cleveland, OH, United States) Solar absorptances and spectral reflectances of 12 metals for temperatures ranging from 300 to 500 K Solar absorptances and spectral reflectances of metals. Show more. Water has high absorption and virtually no reflectance in near infrared wavelengths range and beyond. Optical constants of Cu (Copper) Johnson and Christy 1972: n,k 0.188-1.937 µm In this study, a level analysis of Cu content via spectral indices in the northwestern Junggar region, Xinjiang, was conducted. ohmpercentimetercubeat2i°.8or3.99timesthatofcopper. By continuing you agree to the use of cookies. © 2019 Elsevier B.V. All rights reserved. 4. Copyright © 2020 Elsevier B.V. or its licensors or contributors. In the infrared region (small frequencies), this equation shows that metals with high reflectance also are good conductors. The spectral reflectance curves of samples are shown in Fig. However, approaches for remotely sensing elements are still lacking, particularly for element content. With sensitive wavelengths and a significant correlation coefficient (R2 = 0.63, P < 0.005), the Normalized Difference (ND)-type index was the most sensitive to Cu content exceeding 10,000 ppm. The best wavelength domains for a given type of index were determined from four types of spectral indices by screening all combinations using correlation analysis. It provides data for prospecting in areas without sufficient geochemical data, and thus is of vital significance in prospecting for ores in such regions. Based on four levels (0–100 ppm, 100–1000 ppm, 1000–10,000 ppm, and >10,000 ppm) of Cu content and corresponding spectral reflectance, simple and useful spectral indices for estimating Cu content at different levels were explored.