From the cover -

As parties of adventurers roam the globe in search of treasure, not everything they find will be gold, silver, or precious gems. Sometimes the party will come across more mundane, yet still valuable, commodities that are bought and sold every day and help keep the world economies going. How do you determine what the value of a bundle of animal hides, or a box of ore should be? If a party should 'liberate' a cargo of myrrh from a merchant ship, what price will they get when they sell it in the next port?

To answer this question Tangent Games has created Commodity Cards. Commodity Cards are cards that the GM can print out and use to determine the type, quantity, and value for different commodities. Commodity Cards II: Raw Materials provides 230 new commodity cards that only deals with those commodities that are used to make something else that has an even higher value. In addition to the cards the book includes sets of tables for random commodity generation.

No GM should be without this useful tool to enhance your gaming experience.