gems, topaz, imperial topaz, Brazil, Minas Gerais, Ouro Preto, properies, mineralogy, gemology

This special issue of the German magazine extraLapis focuses entirely on topaz, following earlier monographs by D. B. Hoover (1992) and Mineralogical Record (1995). The issue opens with a German translation by Maximilian Glas of part of Hoover’s “Historical Perspectives” chapter, covering the etymology of the name topaz, its misapplied names, obsolete trade terms like “Oriental topaz,” and nomenclature issues. A major contribution by Dietmar Schwarz follows, detailing topaz’s gemological and mineralogical properties, crystal structure, geological formation, and key localities (Sanarka in Russia, Katlang in Pakistan, Ouro Preto in Brazil), along with a list of giant cut topaz stones (up to 36,853 ct). Schwarz also discusses causes of topaz color, irradiation and heat treatments, detection methods, and typical inclusions, illustrated by Edward Gübelin’s photomicrographs. The second half of the issue explores historic mining localities: Heiner Vollstädt and Bernd Lahl chronicle the Schneckenstein site in Saxony, once the only significant topaz source in Central Europe and now a preserve; this is followed by a reprint of part of Nikolai I. Koksharov’s classic 1855 paper on Russian topaz from the Urals and Transbaikalia.