Is there ever dispute about quality or purity in physical settlement of contracts? If someone buys x tons of zinc, will the product vary depending on where it was sourced? Is copper from China exactly the same as copper from Chile? Would disputes about quality be dealt with privately by LME arbitration? I deal a lot with high spec metals for oil and gas equipment. Whenever I see that the metal a pice has been made from has been sourced from China I worry. They have a bad habit of forging certificates as their quality levels are very low. Some oil companies will not source certain metals from there due to past bad experience.