*This is an abstract only. No full paper is available for
Although known as a powerful technique for the characterisation of minerals, in this study the Corescan® Hyperspectral Core Imager Mark III was used to measure spectral features of coal (in the visible and near infrared and short wave infrared covering 450 to 2500 nm wavelength). The objective of the study was to identify and spectrally discriminate between coal composition at a macroscopic scale (lithotypes: bright, dull, fusain) and coal rank (coal metamorphism) in a 36 metre core. To approach differentiation between lithotypes, organic ratio and gradient maps were created using distinctive features of the spectrum at different wavelengths: 550 nm, 1200 nm and 2400 nm. The albedo at 550 nm of the bright coal bands, which is an average of the spectral reflectance between 540 and 560 nm, was used to extract information about the rank and compared to vitrinite reflectance (Rr per cent) measured at 546 nm using a photomultiplier (or similar device).
The results showed that compositional coal features can be discriminated from the coal ratios and gradients as exemplified in Figure 1. Bright and dull coal lithotypes are readily differentiated, however, differentiating dull from a carbonaceous mudstone requires further examination. On the other hand, albedo at 550 nm showed a similar trend to that of vitrinite reflectance. This particular core was heat affected by a nearby igneous intrusion and the upper part of the seam has higher vitrinite reflectance (around 2.5 per cent Rr) than the lower part (1.2 per cent Rr). Albedo 550 nm also showed higher values in the upper part of the seam than in the lower.
An outstanding result from this technology is the capability to differentiate black rock from black coal material, which is probably related to changes in the molecular structure and texture of the different components of the coal and consequently their brightness (spectral reflectance).
Rodrigues, S, Fonteneau, L and Esterle, J, 2017.
Hyperspectral signature of coal bands – black over black, in Proceedings Tenth
International Mining Geology Conference 2017, pp 457–458 (The Australasian
Institute of Mining and Metallurgy: Melbourne).