#### Special

- default
- default_silent
- no_decal


#### Concrete/Rock

- boulder
- brick
- concrete
- concrete_block
- gravel
- rock
- stone


#### Metal

- chainlink
- iron
- metal
- metalgrate
- metalpanel
- metalvent
- solidmetal


#### Wood

- wood
- wood_crate
- wood_lowdensity
- wood_panel
- wood_plank
- wood_solid


#### Terrain

- antlionsand
- dirt
- grass
- mud
- sand
- slipperyslime


#### Liquid

- slime
- water


#### Frozen

- snow


#### Organic

- alienflesh
- flesh


#### Manufactured

- cardboard
- glass
- paper
- plaster
- plastic
- rubber
- rubbertire
- tile


#### Miscellaneous

- carpet
- ceiling_tile
- computer
- door
- panel
