I want to quickly cover the Geochimica et Cosmochimica Acta for 15 Sep (vol. 405):
Nakashima, D. Friedrich, J. M. Ott, U. Initial 244Pu/238U ratios and seach for presolar SiC in Ca-Al-rich inclusions from CV3 chondrite using noble gas and trace element abundances P. 80 .2025.06.016
Truly, some deep drilling by this paper. The steady progress of mass spectrometry, and general analytical chemistry, means we are doing geophysics/geochem/lab cosmology out to many, many decimal places. This is one example. The measurements of volatile or decaying elements and isotopes have long been used as clocks or other signs. There are also elements that are considered rock-solid for most purposes. Nakashima et al. include both here. Presolar grains (PSGs) are tiny rock bits that had once been dust, floating through space. When our Solar System formed, some of these grit particles got incorporated into larger and larger bodies. But planets and some asteroids retained their early heat, and melted; all traces of PSGs were lost when their atoms blended into the general magma. Other asteroids, though, never got hot enough, and most PSGs are high-temperature enough, that we can find them today if we look hard enough. Grains of microdiamond, silicon carbide, carborundum, and other refractory minerals can be found that have isotope levels of free space, not of our Solar System. They also dissolve and trap gases; these gases, too, show isotope blends different from ours (except helium, which only has two usable isotopes). That’s right, not only can we pick out grains (sometimes as small as hundreds of atoms) that are not from this star system, but we can, if lucky, pick out the gas content trapped within the crystal structure of those grains. A mature field indeed.