This thesis explores the crystal chemistry and thermodynamics of uranyl vanadate minerals, and describes transformations between these and other groups of U minerals. Structural properties of synthetic uranyl vanadate minerals carnotite (K2[(UO2)2(V2O8)•3H2O), curienite (Ba[(UO2)2(V2O8)•5H2O), and francevillite (Ba[(UO2)2(V2O8)•5H2O), are related to thermodynamic data utilizing Normalized Charged Deficiency per Anion (NCDA) calculations. This enables quantification of structural stability from crystal chemical properties and has broad applications for understanding the factors that govern the formation of uranyl (and other) minerals. A new uranyl vanadate mineral, finchite (Sr[(UO2)2(V2O8)]•5H2O), is described, and is the first U(VI) mineral found to contain stoichiometric quantities of Sr. Furthermore, several novel synthetic uranyl vanadate phases are discussed as related to the safe disposal of nuclear waste with further implications for the environmental impact of U mineralogy on natural and anthropogenic radioactive materials.Uraniferous hyalite opal has been analyzed for uranium distribution and concentration and several uranyl minerals including meta-autunite (Ca(UO2)2(PO4)2∙6-8H2O), haiweeite (Ca(UO2)2[Si5O12(OH)2]∙6H2O), uranophane (Ca(UO2)2(HSiO4)∙5H2O), and meta-uranospinite (Ca(UO2)2(AsO4)2∙8H2O)) have been identified in proximity to opal. Paragenetic sequences developed in this work provide insight into the transport and fate of uranium in near-surface environmental regimes.  Also investigated in this work are forensic signatures of U-rich materials. Trace element and U isotope analysis of uraninite, the primary ore mineral for U, and uranium ore concentrate (UOC), an important intermediate material in the nuclear fuel cycle indicate that these forensic signatures remain viable indicators of the geologic origin of radioactive materials through early ore processing. Parallel analysis of uraninite and UOC using both laser ablation (LA) and solution mode (SM) inductively coupled plasma mass spectrometry (ICP-MS) produced corroborating results and expands the techniques by which radioactive materials can be analyzed for forensic signatures. A novel nuclear forensic technique was developed and represents a significant contribution to the nuclear forensics community. The average trace element signatures and factors governing these signatures are discussed and related to the origins of U ores. This technique is used to successfully identify the origin of U-rich materials and can be further applied to classify U deposits of ambiguous geochemical origins.