Tarbesseadmetes

Tarbesseadmetes is a proposed mineral species within the hydrated aluminosilicate group. It is described as a layered silicate with aluminum and silicon tetrahedra forming sheets, linked by hydroxide and water molecules, and with variable substitution by iron and magnesium. In hand specimens it is reported as pale blue to greenish microcrystals, often forming platy aggregates that may occur with other metamorphic minerals such as glaucophane and serpentine.

Discovery and naming of tarbesseadmetes are linked to studies conducted in the blueschist-bearing rocks of the Tarbes region in southwestern France. The name combines the locality Tarbes with the suffix -admetes, a conventional ending used in mineral nomenclature for newly described hydrated alumin silicates. The type material was described in the late 2020s by a collaborative team of mineralogists and metamorphic petrologists.

Occurrence and formation conditions suggest tarbesseadmetes forms in high-pressure, low-temperature metamorphic environments associated with subduction zones. It is typically found in blueschist facies rocks and is commonly associated with minerals such as glaucophane, lawsonite, phengite, and chlorite. The mineral is identified primarily through X-ray diffraction and electron microprobe analysis, which reveal a characteristic diffraction pattern and a composition that varies within the (Al,Fe,Mg)2Si4O10(OH)2·nH2O system.

Properties and significance: If confirmed, tarbesseadmetes would provide insight into hydrous phases present during subduction and metamorphic dehydration reactions, potentially serving as an indicator mineral for fluid presence and metamorphic evolution in subduction zones. Taxonomically, tarbesseadmetes awaits formal approval by the International Mineralogical Association as a recognized mineral species.