Partition coefficients are key to petrological modelling yet hard to estimate independently of measurements. Here we model the partitioning of Cr between garnet and clinopyroxene ab initio. Incorporation of Cr into crystal structures causes strain, and its energetic toll defines whether Cr favours one mineral or another. Comparing to Cr content in metamorphic rocks shows how mineral composition and structure set equilibrium partition coefficients and how kinetics hampers equilibrium.

Zoisite eclogites from the Sanddal area, North-East Greenland, contain numerous textures, such as cusps and neoblasts, which are interpreted as melt-related textures. Mineral chemistry and thermodynamic modeling demonstrate that they were partially melted through the breakdown of hydrous minerals, phengite, paragonite and zoisite. Pressure–temperature phase diagrams show that the eclogites reached a maximum depth of ∼70 km and were partially melted near that depth and during exhumation.

Feldspars constitute about 60 % of the earth's crust. Na-feldspar, Na[AlSi₃O₈], is central to this mineral group. Its structural response to changing conditions of temperature and pressure is complicated. In particular, this applies to the distribution of Al and Si on the atomic sites of its crystal structure. We clarify how this distribution varies in thermodynamic equilibrium with external conditions and provide procedures that allow easy determination of the atomic distribution.

Luxembourgite, ideally AgCuPbBi₄Se₈, is a new selenide discovered at Bivels, Grand Duchy of Luxembourg. The mineral forms tiny fibres deposited on dolomite crystals. Its crystal structure is similar to those of litochlebite and watkinsonite, and can be described as an alternation of two types of anionic layers: a pseudotetragonal layer four atoms thick and a pseudohexagonal layer one atom thick. The species named for the city of Luxembourg, close to its locality of discovery.