corundum, inclusions.5, gems

F.G. Smith’s Historical Development of Inclusion Thermometry is a comprehensive historical and critical review of the use of inclusions in minerals to determine the temperatures and pressures prevailing during crystallization. Drawing upon more than a century of mineralogical, petrographic, and physicochemical research, the book traces the development of inclusion studies from the early nineteenth century through 1953, emphasizing their importance in understanding mineral genesis, hydrothermal processes, pegmatite formation, and ore deposition. Smith reviews the pioneering investigations of Humphry Davy, David Brewster, Henry Clifton Sorby, Ferdinand Zirkel, William Noel Hartley, and numerous later researchers, showing how microscopic observations of trapped fluids, gases, and solids gradually developed into quantitative methods of geological thermometry. Particular attention is given to Sorby’s groundbreaking work of 1858, which established the relationship between the expansion of fluids in sealed mineral cavities, the disappearance of vapor bubbles during heating, and the temperature and pressure of mineral formation. The book examines the classification of primary and secondary inclusions, the mechanisms by which foreign substances become enclosed during crystal growth, and the effects of subsequent recrystallization, deformation, and fluid leakage. Extensive discussion is devoted to aqueous inclusions containing dissolved salts, inclusions containing liquid carbon dioxide, multiphase inclusions with daughter crystals, and glassy inclusions representing trapped silicate melts. Smith evaluates the physical chemistry of water–carbon dioxide systems, the influence of pressure on homogenization temperatures, and the limitations of using such temperatures directly as measures of crystallization conditions. He also reviews decrepitation techniques, in which minerals are heated until internal pressure causes inclusions to rupture, providing another means of investigating their thermal histories. Of particular gemological interest are the numerous historical observations of inclusions in ruby, sapphire, spinel, emerald, aquamarine, topaz, quartz, diamond, garnet, and tourmaline. Smith recounts Brewster’s early experiments with fluid inclusions in topaz and sapphire, including observations of highly expansible liquids subsequently identified as carbon dioxide. The investigations of Sorby and Butler in 1869 receive special attention, particularly their descriptions of two- and three-phase inclusions in ruby and sapphire, complex inclusions in spinel, and fluid and crystalline inclusions in emerald and aquamarine. Studies of oriented mineral inclusions, internal strain, radial fractures, and their relationships to asterism and chatoyancy are also reviewed. Smith discusses the contributions of Eduard Gübelin to the identification and interpretation of inclusions in gemstones, recognizing their significance in distinguishing natural materials from synthetic counterparts and understanding the geological environments in which gems crystallize. The concluding critical synthesis examines the classification and formation of inclusions, the nature of mineral-forming solutions, and the principles and limitations of inclusion geothermometry. Extensive bibliographies arranged by author and subject make the volume an important reference to the early scientific literature. The work provides a valuable historical foundation for modern fluid-inclusion studies and gemological microscopy, documenting the development of techniques that permit microscopic features within crystals to reveal information about their origins and conditions of formation.