TOURMALINE STUDIES: PAST, PRESENT AND THE NEXT 100 YEARS

Since 1946 the Mineralogical Society of America (MSA) has used a tourmaline (tur) cross section emblazoned with “Mineralogy-Crystallography-Petrology” as MSA’s logo to symbolize the integrative, multidisciplinary membership and studies advocated by the society. Appropriately, tur studies also have a distinguished history that reach across disciplinary lines. In fact, tur studies have been an integral part of scientific inquiry for centuries, continue to flourish today and have a bright future. The unusual pyroelectric and piezoelectric properties of tur attracted the attention of 19^th-century scientists; they considered tur key to a grand unification theory of heat, electricity and magnetism. During that time, tur’s occurrence within granites and granitic pegmatites was widely known, but new discoveries increased the range of its known occurrence in igneous, metamorphic, sedimentary rocks and ore deposits.

In the early-mid 20th century with the development of instrumentation, tur studies greatly expanded as characterization of its chemical and physical properties improved. Tur’s piezoelectric properties were utilized for detection and measurement of conventional and atomic explosion pressures. In clastic sedimentary rocks tur was identified as an important heavy mineral that became a means to determine provenance and make stratigraphic correlations. By the 1960-70s, tur’s overall crystal structure and structural formulae were largely deciphered.

More recent studies have demonstrated its vast petrogenetic utility, far-ranging compositions, and extreme pressure-temperature-compositional (P-T-X) stability. Tur has become a valuable indicator mineral in rocks and sediments because of its capacity to obtain a chemical signature of the rock in which it formed and evolved, its ability to retain this chemical imprint through weathering and transport, and its capability to provide specific information on the time, temperature and fluid history at each stage of tur’s development. New analytical tools have opened exciting and significant chemical, crystallographic and spectroscopic possibilities such that the future of tur studies will certainly continue to influence scientific inquiry. Thus, as tur is stable and increasingly valuable for mineralogical studies, so is MSA.