corundum, sources.12, gems

Descriptions are given of gem-quality sapphire and “hyacinth” zircon—and the associated chrome spinel, magnetite, and enstatite—found at Primorye in heavy-mineral concentrates that were ultimately derived from alkali basalts. Transparent blue, blue-green, green, and occasional multicolored sapphires are found as rounded pebbles (2 to 30 mm in size); some star sapphires are recovered. Chemical analyses and visible absorption spectra show that the sapphire coloration is related to the presence of Fe (0.72–1.75 wt.% FeO) and Ti (0.02–0.20 wt.% TiO₂). Inclusions of hercynite and ferrocolumbite were identified in some of these corundums. The zircon also is found as rounded pebbles (1 to 25 mm in size). They are transparent orange, orange-yellow, or brown-red, and become colorless on heating. Their chemical compositions correspond to those of the rare zircon variety naegite, with 4.59–6.14 wt.% Ta₂O₅, 3.22–3.59 wt.% Nb₂O₅, and 3.98–4.09 wt.% ThO₂. [Editor’s note: The terms hyacinth and naegite are not used in most modern gemology and mineralogy references in English.]

corundum, sources.12, Montana.12, gems

This article describes the historical events and fascinating people involved in sapphire mining at Yogo Gulch, Montana. It travels in time from Jake Hoover’s discovery of the translucent blue stones at Yogo Creek in 1895, through the mine’s numerous British and American owners, to the current owner, Roncor Inc. Dr. George F. Kunz, of Tiffany & Co., originally confirmed the identity of the blue pebbles from Jake Hoover’s sluice box as “sapphires of unusual quality.” Jake Hoover stayed involved, eventually taking on partners, until 1897, when he sold his quarter share to his partners for $5,000 so he could join the Alaskan gold rush. Two months later, British interests purchased his share for $100,000.. Production at Yogo started in 1896 and continued almost without interruption until July 1923, when a flash flood destroyed the mine infrastructure. From 1898 through 1923, the Yogo dike yielded 16 million carats of rough sapphire, resulting in 675,000 carats of fine blue cut sapphire worth $25 million. Charles T. Gadsden, appointed mine supervisor in 1902, resided at Yogo from 1903 until his death in 1954, even though the mine (locally known as the English mine) had been inactive for more than 30 years.. In 1956, Yogo returned to American ownership. Since then there has been only minor, intermittent production, by a variety of American owners and lessees, none of which has had significant success. While mining has never progressed deeper than 250 feet (about 77 m), it is believed that the dike exceeds a mile (1.6 km) in depth and contains reserves estimated at 40 million carats of gem-quality rough sapphire. [Editor’s note: For further details, see K. A. Mychaluk, “The Yogo sapphire deposit,” Spring 1995 Gems & Gemology, pp. 28–41.]. Kim Thorup

gems, archaeology, archaeogemology, Pakistan, steatite, Afghanistan, seal stones, grossular garnet, species, locality

A study examined green stones from Pakistan using X-ray diffraction (XRD) to identify ethnographic and archaeological samples of steatite" (soapstone) and other rocks, according to a study published in South Asian Archaeology 1995. This research included elemental analysis, including steatite samples from Pakistan and Afghanistan, and seal samples from Harappa using X-ray fluorescence (XRF) and XRD techniques. The study also investigated the origin of raw materials used in the Indus Valley Civilization, particularly for seals."

gems, spinel, Vietnam, Luc Yen

corundum, Laos.12, gems

corundum, treatments.6, flux healing, gems

gems, jade, jadeite, fei cui, Mesoamerica, Mexico, Guatemala, Costa Rica, Mayans, Olmecs, Aztecs, archaeology, history, archaeogemology, Pre-Columbian jade; Costa Rica; Maya; exchange; iconography, lapidary, Incas, Peru, Colombia, Bolivia

Andean Art at Dumbarton Oaks presents the Andean portion of the Robert Woods Bliss Collection of Pre-Columbian Art. The volume superbly illustrates all 133 Andean objects in color plates and includes numerous complementary and comparative black-and-white illustrations and drawings. The body of Pre-Columbian art that Robert Woods Bliss carefully assembled over more than half a century, between 1912 and 1963, and which has been expanded slightly since his death, constitutes a remarkably significant collection. These works rank among the finest examples of the visual arts produced by Andean cultures. This Andean volume is the first in a planned series of four catalogues devoted to the entirety of the Bliss Pre-Columbian collection. The remaining volumes were intended to focus on objects from eastern Mesoamerica (Olmec and Maya), western Mesoamerica (Teotihuacan, Veracruz, Mixtec, and Aztec), and Lower Central America. Andean Art is composed of five thematic essays, shorter studies on the Andean cultures represented in the collection, and detailed discussions of the individual objects. These contributions were written by specialists in Pre-Columbian art and present the latest scholarly perspectives on Andean cultures and the works themselves. All thirteen authors bring broad expertise in Andean cultural history, archaeology, and art history to their essays, while focusing primarily on the objects in order to provide meaningful contexts and to demonstrate how these artworks, created and used with specific purposes, reveal distinctive qualities of Andean civilization. The volume gives readers a strong sense of how the creators and original owners of the objects in the Bliss collection used and valued these works on many levels. The authors also place individual pieces alongside comparable examples whenever possible. An especially notable feature of the book is the technical analysis of the metal objects contributed by metals specialist Heather Lechtman.

gems, jade, fei cui, pyroxene jade, jadeite, b-jade, treated jade

gems, archaeology, archaeogemology, Central Asia, Kazakhstan, quartz, carnelian, coral, glass, amber, beads, Iran

A woman’s burial in southern Kazakhstan included beads of carnelian, coral, glass, and amber, and bracelets of large amber beads, all described in some detail but not illustrated. Some perhaps came from Iran by trade or as booty.

gems, ancient gemology, ancient jewelry, early metallurgy, historical, ancient trade, Roman Empire, China