A simple method to 'point count' silt using scanning electron microscopy aided by image analysis

This study presents a simple method to 'point count' silt-sized grains using backscattered scanning electron microscopy together with image analysis. The work materialized out of the need to determine the heavy mineral abundance within silt obtained from coastal dunes to aid in the interpretation of dune weathering. This technique allows two broad mineral groups to be quantified according to their modal abundance. The groups are characterized by their dominant atomic elements present; atomic numbers >20 are classified as 'high' (metal oxides, zircon, monazite, carbonates, pyroxenes and amphiboles) and those <20 as 'low' (quartz, feldspars and organics). As a check on this technique, X-ray fluorescence was used. This showed a strong positive correlation (r2=0.85) with the developed point counting technique.