corundum, Tajikistan.12, spinel, geology.11, gems

Sinkankas: “Geology of Gemstone Deposits” taken on a world-wide basis. The first chapter discusses classification schemes, standard cutting styles, prices, synthetics, a genetic scheme of classification with relation to rock massifs, and a world-map showing deposits. The main text studies principal gemstones, other than diamond, namely ruby, sapphire, emerald, opal, beryl, topaz, tourmaline, peridot, garnet, turquoise, amethyst, chrysoprase, and others, with each being given a brief summary of important data followed by descriptions of deposits, country by country. The absence of many gemstones suggests that the study was confined to those that occur in the USSR. The final chapter summarizes occurrences in pegmatites, ultrabasic rocks, effusive rocks, sedimentary rocks, and alluvia. The numerous sketches in the text generally are previously published geological maps, plans, and cross-sections of gemstone deposits or areas, while the colored photographs which lead off the chapters depict the gemstones discussed therein; they are of poor quality. Bibliography appended (!) and includes non-Russian entries.