Vanoxite is a vanadium oxide with water that is, I think, the vanadium equivalent of rust or of rust-like mineral species we see commonly with iron and manganese. However, it seems fairly uncommon. Apparently because it does not crystallize, its IMA status is listed as Questionable/Doubtful as a species although that is a supposition. In any case, the material is present here as dark material in the matrix of carnotite (for which this is an excellent reference specimen)