Ferromanganese crusts and nodules chemical analyses from the USGS Woods Hole analytical laboratories

Beginning in 1983 the USGS searched major oceanographic institution dredge archives for samples and data relevant to the USGS Woods-Hole Ferromanganese Crust Data Base. With the cooperation of the institutions more than 600 samples were collected from twelve institutions and brought to the U.S. Geological Survey Branch of Atlantic Marine Geology in Woods Hole, Mass, for geochemical analysis. At USGS Woods-Hole, 2.0 cm thick mini-slabs from ferromanganese crust or nodule outer surface were separated into horizons and layers. They were ground and sieved through a 105 micron nylon mesh. Remaining ferromanganese material was removed by washing with 10 percent hydroxylamine hydrochloride (NH2OH.HCL) and 1 percent oxalic acid. Samples were first dried at 110°C overnight for the determination of hydroscopic water (H2O-). For some samples, the structural water content was determined by the loss (Loss at Ignition (LOI)) from heating at 500°C for one hour followed by a heating at 1000°C for one more hour. Major and minor element concentrations were determined by X-ray fluorescence spectrometry.