Puerto Rico shoreline placers

Region East, Southeast
Mineral systems
Deposit types
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Based on work by Guillou and Glass (1957) and MRDS data reported by Bawiec (1998). Highest heavy mineral concentrations are noted along the southeast coast, and in locales along the eastern coast. Additional high concentrations noted near river outputs, listed in MRDS.
Identified resources Unknown.
Production None.
Status Unknown.
Estimated resources Unknown.
Geologic maps Cox and Briggs (1973), scale 1:240,000; Briggs and Akers (1965), scale 1:240,000.
Geophysical data Inadequate aeromagnetic, non-existent aeroradiometric data (Bawiec, 1998).
Favorable rocks and structures Quaternary sands, especially near river outputs.
Deposits Occurrences noted near the mouths of Rio Camuy, Rio Grande de Aricibo, Rio Cocal, and along the southern and eastern coasts.
Evidence from mineral occurrences Guillou and Glass (1957).
Geochemical evidence Concentrations of silt- and sand-sized heavy minerals in river samples average 14.6% and 11.9% for the silt and sand fractions, respectively.
Geophysical evidence Unknown.
Evidence from other sources Geologic mapping, geochemistry.
Comments Placers derived from mostly volcanic terranes with some granites; magnetite & pyroxene appear to be the dominant minerals. Some samples also contain ilmenite, zircon, and chromite, and barite. Some magnetite contains 0.24-0.44% V.
Cover thickness and description Exposed or shallow.
Authors Anjana K. Shah.
New data needs Geologic mapping, geophysical data, geochemical data.
Geologic mapping and modeling needs Geologic mapping at 1:24,000 scale.
Geophysical survey and modeling needs Rank 1 or 2 aeromagnetic and radiometric data may assist geologic mapping of sources. Monazite presence unknown; radiometric data may help with imaging.
Digital elevation data needs Lidar complete.