beryl, emerald, inclusions, India, gems

beryl, emerald, Colombia, Chivor-Somondoco, gems

Nice description of the emerald mines in Colombia, particularly at Chivor.

gems, beryl, emerald, Colombia, Muzo, geology

The Muzo Emerald Mines represent the only large emerald deposits that can be successfully mined and that produce the highest quality emeralds known. Although mined in a very primitive way for the last 400 years, Muzo still has quite unpredictable emerald reserves, which do not seem to have diminished after centuries of mining. The invariable relation of the Muzo emeralds with the Cretaceous Villeta shales is quite peculiar and has not yet been given an adequate explanation.

gems, bery, beryl, emerald, Pliny, history of gemology, etymology, Rome, Roman gemology

Pliny the Elder’s chapters on the smaragdus are so lacking in scientific detail that it is impossible to identify exactly the different minerals he includes under this term. Of the twelve varieties he mentions, the first is most probably the only one that ought properly to be translated as “emerald”: quantum smaragdi a gemmis distant, tantum Scythici a ceteris smaragdis. There are, however, two clues in the passage which, considered in light of information provided by other writers, help explain the broad application of the word smaragdus. The mineral in question may have been a hydrated carbonate found in many parts of the world, from Cornwall to Chile. Although its pleasing green color led to its use for ornamental purposes, its opacity excludes identification with at least some of the nine varieties associated by Pliny with copper (37.66): dos eorum est in colore liquido nec diluto, verum ex umido pingui quaque perspicitur.

beryl, emerald, synthetic beryl, emerald, inclusions, gems

corundum, history.1, gems

Ibn al-Akfānī presents a concise medieval Arabic treatise on precious stones, summarizing earlier authorities while adding observations of his own. He treats ruby (yāqūt), balas ruby, garnet, diamond, pearl, emerald, peridot, turquoise, rock crystal, agate, malachite, jasper, bezoar, and other materials, describing their varieties, colors and qualities, principal sources, methods of testing and working, relative values, and reputed medicinal or talismanic properties. Commercial information is particularly valuable, including distinctions of quality and contemporary systems of valuation; diamonds are also discussed as tools for drilling other gemstones. Although traditional lore is repeated, Ibn al-Akfānī sometimes tests inherited claims critically—for example, he reports experimenting with the supposed effect of emerald on snakes and finding it untrue. The work thus combines mineralogical and gemological observation, trade knowledge, lapidary practice, medicine, and traditional stone lore, providing an important account of gemstone knowledge and commerce in the fourteenth-century Islamic world.

gems, beryl, emerald, Colombia, lore

Tastefully-designed, all in same format, and distinguished by use of Rockwell Kent's characteristic drawings as vignettes on each title page in addition to a tipped-in color plate of high quality. The text is in popular vein, with a few technical facts and more on lore and legend. A second printing issued on thinner, whiter paper, and enclosed in a wrap of white, silver-flecked paper, which also used for endpapers. [from Sinkankas]

gems, corundum, history.1, beryl, emerald

gems, jade, jadeite, fei cui, turquoise, France

Forde examines the unusually rich occurrence of greenstone axes and green beads in the megalithic tombs of Brittany, particularly southern Morbihan, and considers their mineralogy, geological sources, archaeological associations, and relationship to the wider megalithic cultures of western Europe. He distinguishes large, finely polished, often point-butted “ceremonial” axes of jadeite, chloromelanite, diorite, and related rocks from the smaller fibrolite axes used more generally, noting that the former frequently show no evidence of practical use and occur prominently in such important tombs as Mané-er-Hroëk, St. Michel, and Tumiac. Reviewing earlier mineralogical analyses, he stresses that objects loosely described as “jadeite” comprise several different materials; genuine jadeite and chloromelanite occur, occasional nephrite axes have been reported, and other specimens are pyroxenites or related rocks. Forde rejects the assumption that their green color necessarily indicates exotic material and argues from the geology of Brittany—including abundant pyroxenites and metamorphic rocks capable of producing jadeite-, actinolite-, and nephrite-bearing differentiates—that the greenstone used for the Breton axes was probably local. He separately examines “callais,” the apple- to emerald-green, sometimes translucent material extensively employed for beads and pendants. Earlier analyses had shown callais to be a hydrous aluminum phosphate related chemically to turquoise but differing in appearance and proportions, its green color being attributed to iron rather than copper. More than 500 callais objects were known from Brittany, while particularly large numbers also occurred in Portugal and smaller quantities elsewhere in France and Iberia. Its geological source remained uncertain, and Forde considers both a Breton source with export southward and an Iberian origin with introduction into Brittany plausible. He interprets the shared occurrence of callais, greenstone axes, bell beakers, and other elements as evidence for close cultural connections between Brittany and Iberia within the western European megalithic tradition, while emphasizing that the Breton ceremonial axes represent a distinctive local development of exceptional craftsmanship. Sinkankas: Describes axes and other objects made from a variety of stones which in some cases are jadeite but in others are some kind of fine-grained greenish rock; callais, however, may be turquoise.

corundum, synthetic corundum.7, gems

Sinkankas: The first chapter introduces the book, treating the history of gemstones in general and reviewing previous attempts to imitate and synthesize gemstones. Ch. 2, problems of nomenclature; 3 summarizes specific features and properties of gemstones; 4, considerable detail on past attempts to synthesize diamond, corundum, spinel, quartz, chalcedony, opal, alexandrite, phenakite, emerald, aquamarine, euclase, topaz, spodumene, zircon, diopside; distinctions between natural and synthetic gemstones. Regarded favorably by L.J. Spencer, Min. Mag., 22, 125, 1929, 67: “useful and concise review of the results that have been obtained in the artificial production of gem minerals, more particularly diamond and corundum … the author believes that H. Moissan succeeded in preparing diamond, but that the results of other experimenters are doubtful.”