Do silica phytoliths really wear mammalian teeth?

There is considerable literature suggesting that silica (opal) phytoliths cause dental enamel microwear in mammals. Much of this literature cites a single study from 1959 as evidence that silica phytoliths are harder than mammalian tooth enamel and so have the potential to cause dental microwear. No other studies using similar methodology have actually confirmed whether phytoliths are harder than dental enamel.     

Glass trade beads in North America: An annotated bibliography

Historical Archaeology -     

Chemical Analysis of 17th‐century Red Glass Trade Beads from Northeastern North America and Amsterdam

Seventeenth‐century opaque red (redwood) glass trade beads of different shapes and sizes were made of mixed alkali (mainly soda)–lime glasses and were coloured with Cu, presumably as cuprous oxide or as finely dispersed elemental Cu. During the early 17th century, beads of all shapes were opacified with Sn; cored beads, with uncoloured cores and hence lower Cu levels, also tended to have slightly lower Sn contents than uncored beads. By the mid‐17th century, cored tubular beads were being opacified with a combination of Sn and Sb, a technological change similar to that observed in white glass trade beads, while uncored redwood beads appear not to have been opacified with either Sn or Sb. Bead chemistries are sufficiently different to allow them to be sorted into subgroups, which may then be tracked in various archaeological sites and regions.