Rare Earth Minerals in Fracture Mineralization in Northern New York

摘要

As part of our ongoing study of the mineralogy of northern New York, we recently used an SEM / EDS system to look for radioactive minerals in the smoky quartz vein at the well known Bower Powers farm near Pierrepont in St. Lawrence County, NY. Some of the quartz from this vein is very dark (Fig. 1) implying a nearby source of radioactivity. Our initial effort yielded uranium peaks in intact samples of the late-stage chlorite from this vein; however, imaging with backscattered electrons showed no minerals with heavy elements on the surfaces of these samples. Following the report by Jared Minges during the 2012 Technical Session of the Rochester Mineralogical Symposium that he found trace minerals distributed throughout coarse calcite in low-temperature hydrothermal mineralization, we decided to look inside the late-stage minerals rather than just on their surfaces. To this end, we used a mortar and pestle to crush both a sample of greenish gray chlorite (probably the last mineral to form in the vein paragenesis) and a sample of coarse tan calcite (probably the first mineral to form) from the same specimen.