Here's our list of object materials:
"cotton",
"leather",
"glass",
"gold",
"organic",
"paper",
"steel",
"wood",
"bone",
"crystal",
"ether",
"adamantine",
"mithril",
"iron",
"copper",
"ceramic",
"satin",
"silk",
"dragonhide",
"burlap",
"velvet",
"platinum",
"obsidian",
"wool",
"onyx",
"ivory",
"brass",
"marble",
"bronze",
"pewter",
"ruby",
"sapphire",
"emerald",
"gemstone",
"granite",
"stone",
"energy",
"hemp",
"diamond",
"earth",
"silver",
"alchemical silver",
"cold iron",
"darkwood",
Here's a neat list of exotic materials too (from d20pfsrd.com):
Adamantine
Angelskin
Blood Crystal
Bone
Bronze
Bulette Armor
Cold Iron
Darkleaf Cloth
Darkwood
Dragonhide
Dragonskin
Eel Hide
Elysian Bronze
Fire-forged steel
Frost-forged steel
Gold
Greenwood
Griffon mane
Living steel
Mithral
Obsidian
SerpentStone
Silver, Alchemical
Silversheen
Stone
Viridium
Voidglass
Whipwood
Wyroot