Synthesis of calcium vanadate minerals and related compounds

Abstract

Synthesis of natural vanadates shows that most of them are stable in an acid environment. Phase studies of a portion of the system CaO-V 2 O 5 -H 2 O indicate that calcium vanadates are an indicator of environmental pH conditions. Some minerals, such as pascoute, indicate rapid evaporation of vanadite solutions; other minerals, such as hewettite, show that slow evaporation took place. Cursory examination of systems K 2 O-UO 2 -(NO 3 ) 2 -V 2 O 5 and CaO-UO 2 (NO 3 ) 2 -V 2 O 5 , both in aqueous solution, has yielded information on the relationships among carnotite, tyuyamunite, and rauvite.