Retrieving Photometric Properties of Granite Pegmatite as a Function of Mineral Contents and Grain Sizes Using the Hapke Radiative Transfer Model

Optical remote sensing has become an important tool for prospecting in the early stages of geological exploration for rare metal deposits. This analysis enables the identification and mapping of lithium (Li)-bearing minerals using multisource and multiscale remote sensing data. However, the mineral composition of granite pegmatite is complex, and the unique spectral characteristics caused by Li in the mineral structure are still uncertain, which also causes problems of low accuracy and a small range in remote sensing prospecting. Therefore, the purpose of this article is to investigate the scattering properties of granite pegmatite and lay the foundation for the subsequent analysis of grain size and mineral abundance inversion using the Hapke model. First, the relationship between particle size and bidirectional reflectance distribution function response is analyzed. Then, the relationship between the single scattering albedo (SSA) and the particle size and the endmember mineral abundances is extended to the qualitative assessment and quantitative inversion by HySpex imaging hyperspectroscopy. The following results are obtained: 1) a linear relationship between the SSA and the particle size in the characteristic zone is established to evaluate the ore-bearing property, and 2) the abundance of endmember minerals can be estimated by using the photometric parameters obtained from multiangle measurements as the input for the Hapke model. Therefore, the inversion model based on the “multiangle–multisource–multiscale” physicochemical characteristics and mineral abundance of granite pegmatite proposed in this article can provide a new reference for the exploration of Li deposits.