Abstract
This paper considers the market trends of the rare earths and how they are strongly influenced by the by-product/co-product nature of their mining and processing. The two main economic minerals for the rare earths are bastnasite and monazite. Monazite is primarily a by-product of mining ilmenite and rutile and is affected by changes in these markets as well as the presence of thorium. Bastnasite is a byproduct of mining iron ore in China and a stand-alone product in the USA. The paper will use conceptional relationships and empirical data to delineate the various by-products/co-products relationships and how they determine observed market behavior.