Miscellany

Just the facts

Sir John Meurig Thomas, ScD, FRS, presented a lecture in Cambridge, England in Jan. 1998 entitled "Microscopic Strucure: Minerals, their Derivatives and Applications". A splendid synopsis of the presentation was reported by M. Moore in the June 98 BCA Newsletter. The following thought provoking comments are from Moore's review. -ed.

The total number of minerals is a mere 3700, or so, compared with more than ten million different chemical compounds. There are four million species of insects (of which 300,000 are beetles). This fact prompted JBS Haldane to remark that he didn't know much about the nature of God, except that He was "inordinately fond of beetles"! Lord Kelvin, wrote in 1904 about the chirality of quartz that there were left and right handed varieties, with slightly more specimens of left than right. There are left and right handed versions of the 100 or so amino acid, the basis of life itself: and Nature appears to use about 20, all of which are left handed. The molecule of the drug Aspirin crystallizes in 29 different forms, which prompted someone to remark that there were "twenty-nine different ways of getting a headache!" The recurring themes throughout Sir John's lecture were the relationships between each individual crystal structure and the properties (chemical and physical) of the substance. Questions such as "Can one play with stoichiometry?" lead into ideas employed in modern materials science and catalysis. Perovskites get their name from a Russian finance minister of the last century and their structures form the basis of most modern high-temperature superconductors. 25000 such structures have been determined in the past decade! Sir John concluded his brilliant lecture with the example of ZSM-5, a porous catalyst synthesized in America in the early 1970's but recently discovered to be naturally occurring by Italian geochemists in Antarctica. It has a structure based upon rings of 10, 6, 5, 5, 5 and 6 members. Amazingly, the same pattern is depicted on the walls of a mosque built in Baku, Azerbaijan in 1086! Sir John finally remarked, "There's nothing new under the Sun!"

M. Moore