"With respect to the question concerning TiO2 in yesterday's email, it is my understanding that rutile is the most common naturally occurring mineral containing TiO2, and like ilmenite, is one of the ores that is mined for titanium. It makes sense to me that rutile itself may not be listed as a traded commodity, in the same way that chalcopyrite may not be a traded commodity, but HG copper is. Perhaps you can think of examples that break this "rule". As a non-expert, it makes sense to me that markets might be more interested in refined, and therefore useful, commodities rather than their source. I enjoy the plethora of interesting comments and sources of information in your service, having subscribed for a few years. May you live an eternity!"

David Fuller's view My observation is that the LME or CME will list futures contracts for a metal when there is sufficient interest among producer and consumer firms to ensure market liquidity, and who can also agree on the benchmark contract to be traded. This inevitably nets out many increasingly important metals which are categorised, often inappropriately, as 'minor metals'.

Thanks for your good wishes and long may you continue to enjoy the service. On longevity, I will try to ensure that my Audios do not seem to go on for an eternity.