Al oxide-sapphire
Al oxide-polycryst
Asphalt
Bakelite
Beryllium oxide
Clay
Coal-anthracite
Concrete & stone mix
Cotton
Fused Silica
Glass-Pyrex
Glass-soda lime
Ice
Paper
Parafin
Rock-granite
Rock-limestone
Rock-marble
Rock-quartzite
Rock-sandstone
Rubber-vulcanized soft
Rubber-vulcanized hard
Sand
Soil
Snow rho=110
Snow rho=500
Sulfur
Teflon
Thorium dioxide
Titanium dioxide
Clay_Smooth
Graphite_Smooth
Silicon Dioxide_Fused
Glass - Soda Lime_Smooth
Rubber_Hard_Black_Smooth
Rubber_Soft_Gray_Smooth