Pichkaev О. V. RussiaСамараSamara State Technical University, 443100, Samara Molodogvardeyskaya street, building №244аспирантlegpichkaev@rambler.ru Author's articles Study of the Stable Tetrahedron LiF-KF-KCl-K2WO4 of the Quinary Reciprocal System Li,K||F,Cl,WO4