The secrets of the sand – Mineralogy of coastal sands and dunes in Marshfield, MA, USA and comparisons to other beach sands

Abstract Using a variety of analytical tools, the mineralogy of the sands and dunes at several public beaches along the coastline near Marshfield, Massachusetts was examined. X-ray powder diffraction analyses combining Rietveld methods, orientation analyses, and clustering techniques were primarily used for mineral identification. The results of the analyses point to the underlying geology, a history of glaciation, and erosion of the underlying bedrock and rocks. The sands could be termed “continental” sands since they reflect the composition of the underlying bedrock. The averaged bulk (>1%) mineral composition of the Marshfield beaches and coastal dunes is very similar and similar to other reported mineralogical analyses of Massachusetts and many New England beaches. Quartz and the alkali feldspars, microcline, and albite, comprise ~90% of dune and beach samples. These are usually followed by muscovite and clinochlore, and varieties of amphibole. Higher albite concentrations and a few characteristic minor phases (i.e., epidote) differentiate this sand from others in the region. When analyzing rocks and rock berms present on all beaches, the mineralogy is much more complex and reflects historic glacial till coverage and glacial retreat, combined with modern erosion and storm impact