The parisite-(Ce) enigma: challenges in the identification of fluorcarbonate minerals.

A multi-methodological study was conducted in order to provide further insight into the structural and compositional complexity of rare earth element (REE) fluorcarbonates, with particular attention to their correct assignment to a mineral species. Polycrystals from La Pita Mine, Municipality de Maripí, Boyacá Department, Colombia, show syntaxic intergrowth of parisite-(Ce) with röntgenite-(Ce) and a phase which is assigned to (i.e.

2/ Postorthopyroxene γ-LiScGeO, a New Dense High-Pressure Polymorph and Its Direct Transformation from the Structure.

Orthorhombic β-LiScGeO single crystals were compressed hydrostatically up to 10.35 GPa using a diamond anvil cell and investigated in situ by means of X-ray diffraction and Raman spectroscopy. Crystal-structure investigations at ambient conditions and at high pressure show a structural transition from an orthopyroxene-type structure ( ≈ 18.