Secondary Minerals and Constituents of the Marcellus Shale Formation

This work identifies unknown crystals found encrusting the Marcellus Shale Formation at the Mapleton Quarry locality in Central Pennsylvania, over the course of a month. The outcrop has been exposed for sufficient time for there to be advanced chemical weathering, allowing for the presence of secondary minerals to form and changes in the composition of the surrounding water table and environment. The crystals found were examined under microscope and by an X Ray Defractometer and were positively identified as small clusters of gypsum, or CaSO4∙2H2O. This gypsum was found in three different appearances, with the crystals being colored red-orange, yellow, ad white to colorless. All three types of segregated crystals were examined and the same conclusion was drawn, despite the possible impurities that iron may have gave to the colored gypsum. Visually, swallow tail twinning and monoclinic crystal forms were apparent in all three of the samples examined. Without the visual identification of the clear crystal group, identification would not have been possible, as the XRD pattern created was consistently terrible, in that no defined peaks could be produced.