Luminescence is a generic term that describes the ability of gemstones and other materials to emit light after energetic excitation of valence electrons. Corresponding to the various types of excitation, and depending on either spontaneous or stimulated energetic recovery from the excited to the ground state, there exist a fairly diverse range of luminescence phenomena and techniques. Current gemstone analysis is dominated by the use of photoluminescence (PL; excitation with light) and cathodoluminescence (CL; excitation with electrons), even though other techniques such as ionoluminescence are increasingly applied.

Luminescence is first commonly used to image internal textures of gems. Minute lateral concentrations variations in trace elements and/or structural defects result in luminescence-distribution patterns that are most sensitive in giving hints to primary growth (such as used in distinguishing naturally and lab-grown diamond) and secondary alteration processes (such as used in revealing diffusion enhancement). Second, spectroscopic analysis of the emission facilitates sound interpretation of the luminescence’s origin and assists in understanding reasons for internal textures. Hyperspectral mapping represents a combination of the two approaches.

This keynote lecture attempts to summarise luminescence current applications in gemstone analysis. In an introduction, also some terminology issues (ambiguous use of “persistent luminescence” and “afterglow”; luminescence versus fluorescence) will be discussed. Presented research examples include the application of excitation spectroscopy in unravelling diffusion treatment, the use of hyperspectral mapping to estimate self-irradiation damage, non-destructive gem analysis in historic objects of art, and changes in PL spectra resulting from heat treatment of gems.

Lunar meteorites are a key source of information for understanding the Moon’s geochemical structure and evolutionary history. Unlike Apollo samples, they originate from diverse and often unsampled regions, offering broader insights into volcanic activity, impact events, and differentiation processes. Each meteorite type provides a unique glimpse into different lunar periods, contributing to a more comprehensive understanding of the Moon’s evolution.

A crucial aspect of their study is the detailed investigation of mineral phases. Key questions include the growth history of minerals, chemical zoning, fluid inclusions, and overprinting by melts or impacts. Raman spectroscopy is employed for initial, non-destructive mineral identification. This is followed by electron microprobe analysis and scanning electron microscopy (SEM) for high-resolution compositional data.

The Mineralogical State Collection Munich (MSM) operates a dedicated Raman laboratory and maintains the MSM-MRD database, a growing reference for laboratory and in-situ spectroscopy. Lunar meteorites significantly contribute to this database, enhancing Raman spectral libraries essential for future space missions using remote sensing and in-situ analysis.

Beyond lunar samples, our research includes meteorites from Mars, Vesta, pallasites, and chondrites. These are compared with terrestrial analogs—such as mantle xenoliths and ophiolitic rocks—to better understand planetary differentiation and magmatic evolution. Lunar meteorites, in particular, offer a more representative view of the Moon’s surface and chemistry than Apollo samples alone.

This work supports the advancement of planetary spectroscopy, contributing to the interpretation of spectroscopic data and preparing the ground for future robotic and human exploration missions.

Chondrules are among the oldest solid components of our solar system and provide important clues to its early development. Especially inversely zoned chondrules (IZ chondrules) have been little studied so far and could provide new insights into the formation processes of the solar nebula. In this study, we make additionally analyse to the chemical and structural composition of IZ chondrules using optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), backscattered electron imaging (BSE), electron backscatter diffraction (EBSD) and Raman spectroscopy. Our investigations show that IZ chondrules have a core of Mg-rich pyroxene surrounded by an olivine rim. The high Fe content of the olivines (Fa 39-41 %), which is significantly higher than that of other chondrites, is remarkable. The core consists of radially arranged pyroxene crystals, with Mg-rich olivines (Fa34) occasionally occurring in the interior. The textural and chemical zoning indicates that these chondrules were formed in the earliest stages of the solar system and differ from classical chondrules. The formation of the pyroxene core is probably due to a rapid cooling of the protoplanetary nebula (500-2500 K/h). This was followed by a reheating to 1600-1800 K, which formed the olivine mantle. Another possibility was a subtle change in the composition of the chondrule, which may cause a shift in the liquidus phases from low ca pyroxene to iron-containing olivine. These results provide new insights into the diversity of chondrule formation processes and contribute to a better understanding of the early evolution of our solar system.

Serpentinites, formed through hydration of ultramafic rocks, have long been known to play a pivotal role in rock-water interaction accompanying plate-tectonic processes along divergent and convergent margins. Lately, they have attracted growing geoscientific interest due to their role in hydrogen generation and carbon sequestration by mineral carbonation. Serpentine group minerals, as their main constituents, occur naturally in three main varieties: antigorite, lizardite, and chrysotile. Traditionally identified by X-ray diffraction (XRD) and electron microscopy, homogeneous serpentines can also be effectively distinguished using Raman spectroscopy based on characteristic spectra. A critical question remains: Can Raman spectroscopy offer clear identification of serpentine varieties in natural, heterogeneous serpentinites?

For this study we applied Raman spectroscopy to serpentinites from Zöblitz in the Erzgebirge (Saxony). The serpentinites are hosted in quartzofeldspathic gneisses that underwent high-pressure metamorphism during the Variscan orogeny. They show a range of macroscopic textures, from garnet-bearing, highly serpentinized peridotites with isotropic matrices to decimeter-scale banded serpentinites. Raman spectra were collected through spatial mapping both in low (200–1350 cm⁻¹) and high (3200–3950 cm⁻¹) wavenumber regions on polished thin sections. The mapped areas were also examined using polarization microscopy.

Data processing involved analyzing peak parameters (peak position, full width at half maximum) and comparing spectra to reference data using classical least squares (CLS) fitting. The domains investigated, pre-characterized by polarization microscopy, showed clear microstructural heterogeneities linked to optical and morphological differences, all reflected in distinct Raman spectra. Comparing characteristic peak parameters, CLS fitting, and polarization microscopy enabled confident identification of the main serpentine varieties.