According to 12 CFR 32.2 [Title 12 -- Banks and Banking; Chapter I -- Comptroller of the Currency, Department of the Treasury; Part 32 -- Lending Limits] readily marketable staple means “an article of commerce, agriculture, or industry, such as wheat and other grains, cotton, wool, and basic metals such as tin, copper and lead, in the form of standardized interchangeable units, that is easy to sell in a market with sufficiently frequent price quotations.
(1) An article comes within this definition if –
a. The exact price is easy to determine; and
b. The staple itself is easy to sell at any time at a price that would not be considerably less than the amount at which it is valued as collateral.”