Chemical zoning; Unconventional barometry; STRUCTURE + TEXTURE + FABRICS (PETROGRAPHY); MICROTEXTURES (CRYSTALLOGRAPHY); RHODOPE MOUNTAINS (MOUNTAINS OF THE BALKANS); STACKING FAULTS, GRAIN BOUNDARIES, INTERFACES, DOMAINS (CRYSTALLOGRAPHY); CRYSTAL GROWTH/IN SOLIDS, DIFFUSION; STRUKTUR + TEXTUR + GEFÜGE (PETROGRAPHIE); ZONING, ZONAL STRUCTURE (PETROGRAPHY); MIKROTEXTUREN (KRISTALLOGRAPHIE); STAPELFEHLER, KORNGRENZEN, INNERE GRENZFLÄCHE, DOMÄNEN (KRISTALLOGRAPHIE); KRISTALLWACHSTUM/IN FESTEN KÖRPERN, DIFFUSIONSVORGÄNGE; Chemical diffusion; Grain boundary diffusion; ZONARSTRUKTUR (PETROGRAPHIE); Pressure variations; RHODOPEN-GEBIRGE (GEBIRGE DES BALKANS)