The heavy mineral sands of Spurn Head

Spurn head is a spit which has formed due to longshore drift of materials, derived from the erosion of the glacial boulder clay. Heavy mineral placer deposits form mainly due to free settling and entrainment, as well as selective grain transport and shear sorting, forming in the inner surf zone of the beach. Typically the beach has parallel lamination, reverse grading, dark (heavy mineral) layers, and pebbly basal layers. Variation in the heavy mineral contents is seen, with an average of 23%, they are more concentrated in the finer fractions, but generally the sands are well sorted. The heavy mineral content is dominated by limonite, magnetite, garnet, staurolite and ilmenite with lesser amounts of kyanite, rutile, zircon, pyroxene, barytes, apatite, monazite, chromite, pyrite and sphene. The major element chemistry shows a decrease in silica and an increase in total iron, MgO, MnO and TiO2 with an increase in heavy mineral content. The zirconium content increases with a decrease in grain size, but it only reaches 7000 ppm (0.7%) in the most concentrated sample. The Spurn Head heavy minerals are derived from the glacial boulder clay, in turn derived mainly from the Millstone Grit and Triassic sandstones, and these in turn have an origin in the Scottish-Scandinavian Caledonides. The main sources for the import of heavy minerals are covered as well as the major uses. Mineral economics indicate only sample one is 'economic' and it is concluded that overall the heavy mineral sands of Spurn Head are not economically viable.