Raman spectroscopy of fine-grained hydrothermal alteration minerals, and phyllosilicates in particular, presents certain challenges. However, given the increasingly widespread recognition of field portable visible–near infrared–shortwave infrared (Vis-NIR-SWIR) spectroscopy as a valuable tool in the mineral exploration industry, Raman microspectroscopy has promise as an approach for developing detailed complementary information on hydrothermal alteration phases in ore-forming systems. Here we present exemplar high-quality Raman and Vis-NIR-SWIR spectra of four key hydrothermal alteration minerals (pyrophyllite, white mica, chlorite, and alunite) that are common in precious metal epithermal systems, from deposits on the island of Newfoundland, Canada. The results reported here demonstrate that Raman microspectroscopy can accurately characterize pyrophyllite, white mica, chlorite, and alunite and provide details on their compositional variation at the microscale. In particular, spectral differences in the 1000–1150 cm⁻¹ white mica Raman band allows the distinction between low-Tschermak phases (muscovite, paragonite) and phases with higher degrees of Tschermak substitution (phengitic white mica composition). The peak position of the main chlorite Raman band shifts between 683 cm⁻¹ for Mg-rich chlorite and 665 cm⁻¹ for Fe-rich chlorite and can be therefore used for semiquantitative estimation of the Fe²⁺ content in chlorite. Furthermore, while Vis-NIR-SWIR macrospectroscopy allows the rapid identification of the overall composition of the most abundant hydrothermal alteration mineral in a given sample, Raman microspectroscopy provides an in-depth spectral and chemical characterization of individual mineral grains, preserving the spatial and paragenetic context of each mineral and allowing for the distinction of chemical variation between (and within) different mineral grains. This is particularly useful in the case of alunite, white mica, and chlorite, minerals with extensive solid solution, where microscale characterization can provide information on the alteration zonation useful for mineral exploration and provide insight into mineral deposit genesis.

细粒热液蚀变矿物，特别是页硅酸盐的拉曼光谱存在一定的挑战。然而，鉴于现场便携式可见-近红外-短波红外 (Vis-NIR-SWIR) 光谱作为矿产勘探行业的宝贵工具得到越来越广泛的认可，拉曼显微光谱有望成为开发热液蚀变详细补充信息的一种方法成矿系统中的相。在这里，我们展示了加拿大纽芬兰岛沉积物在贵金属超热液系统中常见的四种关键热液蚀变矿物（叶蜡石、白云母、绿泥石和明矾石）的示例性高质量拉曼和 Vis-NIR-SWIR 光谱. 此处报告的结果表明，拉曼显微光谱可以准确表征叶蜡石、白云母、绿泥石和明矾石，并提供有关它们在微观尺度上的成分变化的详细信息。特别是 1000–1150 cm 的光谱差异^-1白云母拉曼谱带可以区分低 Tschermak 相（白云母、白云母）和具有较高 Tschermak 取代度的相（苯酚白云母组合物）。主要绿泥石拉曼谱带的峰值位置在富镁绿泥石的683 cm ^-1和富铁绿泥石的 665 cm ^-1之间移动，因此可用于 Fe ^{2+ 的}半定量估计亚氯酸盐中的含量。此外，虽然 Vis-NIR-SWIR 宏观光谱允许快速识别给定样品中最丰富的热液蚀变矿物的整体组成，但拉曼显微光谱提供单个矿物颗粒的深入光谱和化学表征，保留空间和共生每种矿物的背景，并允许区分不同矿物颗粒之间（和内部）的化学变化。这对于具有广泛固溶体的明矾石、白云母和绿泥石矿物特别有用，在这些矿物中，微尺度表征可以提供对矿物勘探有用的蚀变带信息，并提供对矿床成因的深入了解。