For near-future missions planed for Mars Sample Return (MSR), an international working group organized by the Committee on Space Research (COSPAR) developed the sample safety assessment framework (SSAF). For the SSAF, analytical instruments were selected by taking the practical limitations of hosting them within a facility with the highest level of biosafety precautions (biosafety level 4) and the precious nature of returned samples into account. To prepare for MSR, analytical instruments of high sensitivity need to be tested on effective Mars analogue materials. As an analogue material, we selected a rock core of basalt, a prominent rock type on the Martian surface. Two basalt samples with aqueous alteration cached in Jezero crater by the Perseverance rover are planned to be returned to Earth. Our previously published analytical procedures using destructive but spatially sensitive instruments such as nanoscale secondary ion mass spectrometry (NanoSIMS) and transmission electron microscopy coupled to energy-dispersive spectroscopy revealed microbial colonization at clay-filled fractures. With an aim to test the capability of an analytical instrument listed in SSAF, we now extend that work to conventional Fourier transform infrared (FT-IR) microscopy with a spatial resolution of 10 μm. Although Fe-rich smectite called nontronite was identified after crushing some portion of the rock core sample into powder, the application of conventional FT-IR microscopy is limited to a sample thickness of <30 μm. In order to obtain IR-based spectra without destructive preparation, a new technique called optical-photothermal infrared (O-PTIR) spectroscopy with a spatial resolution of 0.5 μm was applied to a 100 μm thick section of the rock core. By O-PTIR spectroscopic analysis of the clay-filled fracture, we obtained in-situ spectra diagnostic to microbial cells, consistent with our previously published data obtained by NanoSIMS. In addition, nontronite identification was also possible by O-PTIR spectroscopic analysis. From these results, O-PTIR spectroscopy is suggested be superior to deep ultraviolet fluorescence microscopy/μ-Raman spectroscopy, particularly for smectite identification. A simultaneous acquisition of the spatial distribution of structural motifs associated with biomolecules and smectites is critical for distinguishing biological material in samples as well as characterizing an abiotic background.

Laterite could play a crucial role in soil stabilization and environmental remediation, but its internal particle interaction mechanism remains unclear. This study, based on molecular dynamics simulations, used umbrella sampling methods to measure the interaction strength between amorphous alumina and montmorillonite particles in laterite. The mechanisms were explored using differential charge density analysis and bond energy analysis. The results show that the interaction process between alumina and montmorillonite exhibited initial repulsion, then attraction, followed again by repulsion. Calcium ion-induced polarization, the negative charge on the alumina surface and the bonding strength during adsorption played key roles in this interaction. Notably, the bond energy measurement results in this study are consistent with data from other related research, validating the data’s accuracy. These findings improve our understanding of the microscopic mechanisms of laterite particle interactions, providing a scientific basis for its application in soil stabilization and environmental remediation.

Earth’s land cover consists of forests, agricultural land, urban settlements and a large, heterogeneous category that includes deserts, grasslands, savannas, shrublands and tundra. This heterogeneous category has eluded a collective designation comparable to that of forests, which has contributed to its omission from multilateral programs and critical global initiatives. Potential designations for this land category – drylands, grasslands, grassy biomes, open ecosystems and rangelands – were evaluated for their relative advantages and disadvantages. Grassy biome is recommended as the most appropriate designation because it conveys a meaning that is distinct from forests, emphasizes that grasses often coexist with other plant growth forms and has great utility for use by multilateral organizations. However, the criteria of tree canopy cover >10% used by the Food and Agriculture Organization (FAO) to define forests represents a major obstacle to implementation of the grassy biome designation. This minimal canopy cover infringes on global savannas that occupy 20–25% of global land area. An assessment of the functional plant traits determining the shade and fire tolerance of savanna and forest trees indicates that a minimal tree canopy cover of 45% represents an ecologically appropriate demarcation between savannas and forests.

The new ixiolite-group mineral nioboixiolite-(Fe3+), ideally (Nb0.5Fe3+0.5)O2, was discovered in nosean sanidinite of the Laach Lake (Laacher See) volcano, Eifel region, Rhineland-Palatinate, Germany. The associated minerals are sanidine, K-bearing albite, nosean, biotite, Nb-rich ilmenite, Ti-rich magnetite, hercynite, corundum, samarskite-(Y), ekebergite and columbite-(Fe). Nioboixiolite-(Fe3+) forms long prismatic to acicular crystals up to 0.03 × 0.06 × 1 mm and epitaxial intergrowths with ilmenite and intermediate members of the samarskite–ekebergite series. Both colour and streak are black and the lustre is submetallic. The new mineral is brittle, with the Vickers’ micro-indentation hardness of 499 kg mm–2 which corresponds to the Mohs’ hardness of 5. No cleavage is observed. The fracture is conchoidal. The calculated density is 5.033 g·cm–3. In reflected light, nioboixiolite-(Fe3+) is grey, no pleochroism is observed. The reflectance values (Rmin, %/Rmax, %/λ, nm) are: 14.7/16.4/470, 14.3/15.9/546, 14.1/15.7/589 and 14.0/15.8/650. The Raman spectrum shows bands corresponding to stretching vibrations of (Nb,Ti)–O–(Nb,Ti) and (Nb,Ti)–O–Mn2+ and the absence of bands of OH groups. The chemical composition is (electron microprobe data, wt.%): MgO 0.41, MnO 3.52, Al2O3 0.42, Cr2O3 0.75, Fe2O3 20.23, TiO2 22.26, ZrO2 0.76, Nb2O5 51.82, total 100.17. The empirical formula is (Mg0.04Mn2+0.20)Σ0.24(Al0.03Cr0.04Fe3+1.01)Σ1.08(Ti1.11Zr0.02)Σ1.13Nb1.55O8 (Z = 1). The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 3.586 (29) (110), 2.917 (100) (111), 2.503 (18) (002), 2.170 (18) (121), 1.738 (22) (130), 1.689 (26) (221). The crystal structure was determined using single-crystal X-ray diffraction data and refined to R = 0.0447. Nioboixiolite-(Fe3+) is orthorhombic with space group Pbcn, a = 4.6578(6), b = 5.6230(7), c = 5.0182(5) Å and V = 131.43(3) Å3. The new mineral is isostructural with other members of the ixiolite group.