Laterites in Puerto Rico may be an unrecognized critical mineral and metal resource within the U.S. Territories. Nickel and cobalt laterite deposits are extremely important resources and are estimated to hold 60 to 70% of global land-based nickel reserves. It is a challenge to quantify useful or dangerous elements within laterite, as its abundance, variability, and forms are not well constrained. It is useful to understand the variation of elements that can serve important uses or be contaminants, or both. For example, nickel, chromium, and cobalt are all useful but can be hazardous pollutants, especially when inhaled in particulate form. The focus of this research is to provide new insights into the composition of laterites from western Puerto Rico and their relevance in ore forming processes and potential geogenic health hazards.

Laterite and bedrock samples were collected from Carr in western Puerto Rico (18.129665 N, 67.159457 W) and initial handheld bulk X-ray fluorescence (XRF) analysis was conducted. From the rock chips and soil material rock powders were produced. Mineralogy and bulk chemical composition were determined using powder X-ray diffraction (XRD) to define their mineralogy, transmission electron microscopy energy dispersive spectroscopy (TEM-EDS). Lastly, elements within the sample were analyzed using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS).