CATCH THE RAINBOW: GEOCHEMICAL ANALYSIS OF COLORED SLAG FROM IRONVILLE, ADIRONDACK STATE PARK, NEW YORK

Iron was extensively mined and smelted in the Adirondack Mountain Region during the 19th century. Smelting resulted in multiple slag piles in upstate New York. Ironville, located on the eastern margin of Adirondack state park near the southern tip of Lake Champlain, was the first smelting site to use to use an electromagnet for beneficiation. It is considered to be the birth place of the electric age in the United States. Smelting of magnetite for the Crown Point Iron Company began in Ironville in 1828 and continued until 1870. The current slag pile at Ironville covers ~ 4,000 square feet; however a large central portion of the pile has been removed. The slag is highly variegated in color, has a vesicular to ropey appearance and is often glassy. Ironville slag is macroscopically unlike any other slag found in this area of the Adirondack region.

A clean face was dug into the slag pile to expose stratigraphy and color variations. Samples of blue, green, purple, black, and white slag were collected and analyzed with XRD, XRF, transmitted light microscopy, and cathodoluminescence. Soil samples were also analyzed to determine the degree of chemical interaction between the slag pile and its immediate surroundings. Initial findings indicate little chemical difference in major element concentrations for the slag samples. All slag regardless of color show high concentrations of SiO₂ and CaO. An indirect relationship between CaO and Fe₂O₃ has also been noted. Slag samples of the same color do have a distinct trace element signature unique to that specific color group. For example, dark green slag contains significantly more Cr (~136 ppm) than any other color from Ironville and all dark colored slags are enriched in Cu compared to their lighter counterparts. This chemical data is essential to understanding the impact of a historical industrial waste site on this region of New York.