THE USGS ASSESSMENT OF PUERTO RICO'S MINERAL RESOURCES AVAILABLE FOR RECONSTRUCTION IN THE WAKE OF 2 CATEGORY 5 HURRICANES IN 2017

In 2017, category 5 hurricanes Irma and Maria devastated Puerto Rico causing over 3,000 deaths and estimated damages of $90B to roads, bridges, dams, houses and other buildings. The USGS shifted the focus of an ongoing Greater Antilles mineral resource assessment to the island's resources available for infrastructure reconstruction and its ability to import other critical resources.

Primary reconstruction resources include andesite and basalt in the interior highlands and limestone along the northern and southern flanks of the highlands. Volcanic rocks used as aggregate with for repairing asphalt roads, road base, gabions and riprap for shore facilities, bridges and dams with most quarries located near San Juan and in the SW part of the island. Limestone used primarily for cement and aggregate for cement blocks in housing and other buildings is quarried by international conglomerates near Ponce and west of San Juan. Smaller rock quarries are locally owned.

A number of factors have adversely affected the availability of industrial mineral resources. The recent recession depressed construction and related mining and maintenance of mining equipment. The only cement kiln in southern Puerto Rico ceased operations in 2017, and that cement plant now must ship clinker by barge from Turkey. The only active kiln is in northern Puerto Rico. Availability of quartz sand used in concrete is restricted because tourism use restricts the availability of beach sand, the "Sand Act" prohibits the importation of sand from locations other than the continental U.S., and the “Jones Act” requires goods shipped between U.S. ports to be transported on ships that are built, owned and operated by US citizens or permanent residents, and few barges were available for sand transportation after the hurricanes. Some quarries are no longer available for their mineral resources as they have been converted to housing or landfills sites, while at least one is being used as a collection site for tree waste damaged by the hurricanes. The U.S. Army Corps of Engineers was processing 400,000 cubic yards of tree waste in one of these quarries with no identified end use of the processed material. Also, industrial mineral resources were poorly known and this assessment with new lithogeochemical data and an updated geologic map will aid in Puerto Rico’s reconstruction.