Uranium mineral deposits in the vicinity of Chihuahua City (northern Mexico) have motivated a multidisciplinary investigation due to their techno-environmental importance. It provides a broad scope study of representative mineral samples extracted from the San Marcos deposit, located northwest of Chihuahua City. The zone of interest in the source of the Sacramento River, which runs at Chihuahua City. The high uranium content of the San Marcos deposit, which was formed by hydrothermal mineralization, has resulted in elevated levels of uranium in surface and ground water, fish plants and sediments in this region. Mineral identification of the uranium-bearing phases was accomplished with a suite of techniques. Among these phases are those called metalyuyamunite (Ca(UO2)2(VO4)2.3-4 H2O) and becquerelite [Ca(UO2)6O4(OH)6.8(H2O)]. It was decided to study an almost pure metalyuyamunite sample extracted from Peña Blanca Chihuahuan uranium ore and to synthesize the becquerelite, using a modifie procedure from a published one. In the current work the crystal structure of metatyuyamunite is presented, resolved by the Rietveld refinement. Both samples were studied by X-ray Absorption Fine Structure at Beamline 2-3, Standford Synchrotron Radiation Lightsource. In the present work both the spectra and Extended X-ray Absorption Fine Structure parameters are presented.