Abstract: A dense or heavy liquid for material separations comprising an aqueous solution including a salt having anionic moieties having the formula [(a).sup.n+ (b).sub.m O.sub.k ].sup.x- where (a) is selected from group IV elements, group V elements, transition metal elements, and rare earth elements; (b) is one or more transition metal elements having an atomic weight between 50 and 201 inclusive, where O is oxygen, where m is an integer between 6 and 18 inclusive, and where k is an integer between 24 and 62 inclusive, said dense liquid also comprising in said aqueous solution cationic moieties capable of forming said salt of said anionic moieties. The cation values may be lithium, sodium, or a mix thereof, with a small amount of hydrogen cations provided by free acid anionic moieties. The most preferred anionic moiety is [SiW.sub.12 O.sub.40 ].sup.4-. The atom designated (b) alternatively may be molybdenum, vanadium, niobium or tantalum.