opal, treatments, gems

SEVERAL parcels of dyed black opals have recently been offered in the European market. I am indebted to Mr. Arthur A. Wirth of Sydney, Australia, who kindly enabled me to acquire a number of treated black opals of varying quality for investigation.

Gilson, Chatham, Zerfass, Farben, 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

Sinkankas: Historical note on the formation of the collection, its public exhibitions, and final resting place in a special building upon the Dumbarton Oaks grounds, Washington, D.C. The three sketch maps correspond with the collection & catalog arrangement, ie, artifacts from the three broad regions of Mesoamerica, Costa Rica-Colombia, and Andean region. There are 425 items, the largest portion of jadeite objects and other hard and soft stones, illustrated on the many excellent plates. Other classes of artifacts: ceramics, metals, textiles.

gems, jade, jadeite, fei cui, Mesoamerica, Mexico, Guatemala, Costa Rica, Mayans, Olmecs, Aztecs, archaeology, history, archaeogemology

Pre-Hispanic art, art of New Spain, modern art, folk art—these designations are more than aesthetic terminology; the periods they refer to are also stages in the formation of our national existence. The collection of sculpture, paintings, ritual objects and domestic tools, toys and ornaments which is now offered the American public represents a vertical section of Mexican life since its first beginnings until our time. We want to show, not only a number of remarkable works and objects, but also a truthful and varied picture of “Mexican man”, a picture in which the native and the European heritages merge. We wish to render the original character of Mexican art, which in its various historical periods, throughout three millennia, has always been closely connected with life. In this sense one can affirm that art has been necessary, even in its most fantastic manifestations, to the Indian creators, to the Baroque artists, and to the contemporary artists. The presence of man on American soil, where he probably came from Asia, can be traced back about 25,000 years. The oldest material vestiges suggest a stage corresponding to the ethnic groups of the earlier Stone Age. In central Mexico fossil remains about 11,000 years old have been found. The first inhabitants of the country were mammoth hunters. But the populations that we have been able to obtain information about lived much later: about 1,500 B.C. It is still a source of much speculation among specialists that already fully constituted societies, whose immediate antecedents we are even now unable to define, appeared at the same time. In this period the division into two zones, which remained the same in all essentials till the Spanish Conquest, took place: the northern zone, mainly populated by nomads, and the southern zone of agriculture, political organization, the great religions and the great epochs of artistic style. The latter zone covered a territory, bordering on the 23rd parallel to the north, and including Costa Rica to the south. These two zones are designated by the term Mesoamerica. In order to facilitate an understanding of the pre-Hispanic world we have preferred a disposition that emphasizes the interrelative connections of the various styles to a purely chronological or geographical one, without disrupting the continuity of the cultures.

gems, jade, pyroxene jade, fei cui, jadeite, dyed lavender jade, treated jade

Although we were aware that lavender-dyed jadeite is on the market, because we have purchased some for our collection, we have rarely been asked to identify it. Recently, we examined a bead necklace that proved to be pink-fluorescing, lavender-dyed jadeite showing a distinctive spectrum (Figure 7). The dyed stones in our collection do not show either reaction.

gems, early lapidaries, early gemology, early mineralogy, Albertus Magnus

As is well known, the much-praised Summa philosophiae, which was almost universally counted among the works of Grosseteste but cannot have been written by him, refers several times to Albertus Magnus. For these references—made without citing specific works by Albert—corresponding passages have already been identified in Albert’s writings. According to this, the relationship of the Summa to Albert consists in the fact that the author frequently considers Albert’s opinions based on his writings, generally rejects them, but occasionally—especially in mineralogy—praises his explanations. However, the identification of the texts by Albert meant by the author has not been fully satisfactory in every case, and the question remains whether the Summa’s engagement with Albert’s works might not go even further and deeper. It goes further and deeper. It can now be demonstrated which works of Albert the author of the Summa actually had in view and at hand in the passages where he refers to Albert, and how and to what extent he used them. He frequently incorporated them extensively into his own work—not merely quoting them sentence by sentence, but often copying them so fully that entire chapters are little more than extracts from a work by Albert. This order of presentation, however, does not reflect the order of discovery; in this case, recognition of dependency preceded the identification of the citations. The result will likely have less impact on the dating of the Summa than on its evaluation, which in the future will probably be more tempered than it has been up to now.

corundum, sapphire, Umba Valley, Tanzania.12, East Africa, gems

corundum, ruby, Tanzania.12, East Africa.12, gems

Bank describes a ruby-bearing zoisite-amphibolite from Tanganyika (present-day Tanzania), a material that had recently attracted attention both mineralogically and as an ornamental stone. The rock consists principally of green zoisite and dark amphibole containing conspicuous red to purplish-red ruby crystals, producing the striking color contrast characteristic of the material. The constituent minerals and their physical and optical properties are examined, with particular attention to the ruby and zoisite, and the occurrence is considered in relation to its geological setting and mineral associations. The paper discusses the identification and gemological characteristics of the material and its suitability for cutting and polishing, documenting an unusual natural association in which ruby occurs embedded in a contrasting green zoisite-rich matrix.

gems, ancient gemology, ancient jewelry, Egypt, Egyptian jewelry

The majesty and splendor of ancient Egypt were largely due to the remarkably advanced technological skills developed by its artisans and craftsmen. This comprehensive and detailed study of ancient Egyptian technology meticulously documents how these workers, along with other Egyptians, exploited the land’s abundant resources. First published in 1926 and later revised and enlarged, this monumental work became a standard reference, unmatched in any other field of archaeology. The present volume reprints the fourth edition, thoroughly revised in light of more recent research and archaeological discoveries. Topics covered include a wide range of materials and techniques central to Egyptian life: the use of animal products, building materials, cosmetics, perfumes, incense, fibers, glazed ware, glass and its production, metals and alloys, painting materials, pottery, woodworking, precious and semi-precious stones, distillation of alcoholic beverages, and substances used in mummification. Profoundly erudite and rich in detail, Ancient Egyptian Materials and Industries is an indispensable reference for students of Egyptology and classical civilizations, and a vital resource for anyone interested in the long and remarkable history of technological innovation. Sinkankas: Drastically revised, rearranged: the substances now include beverages, animal products, building materials, cosmetics, perfumes & incense, ceramics & glass, fibers, metals & alloys, mummification materials, oils, fats, waxes, painting materials, pottery & its manufacture, gemstones, other stones, woods & woodworking, and a historical analysis. Ch 12, [335–54], on gemstones, among which now additionally appear coral, amber, malachite, and jade, while horn, ivory, nacre and tortoiseshell are described in Ch 2. Ornamental stones are treated in Ch 13, [355–75]. The author notes that “diamond, opal, ruby and sapphire were not known to the ancient Egyptians.” In his preface, Harris notes the inclusion of information taken from recent studies, with references added to the list in the previous edition. Much technological information is also added, with an appendix of reliable chemical analyses. “The most consistent modification has, however, been in matters of lexicography, in order to eliminate invalid evidence derived from inaccurate or disputed translations of Egyptian texts.” In this connection, see also Harris’ Lexicographical Studies in Ancient Egyptian Materials, 1961. In this edition, the following places are of gemological interest: beads, Ch 4, [41–7] (includes gemstone materials); inlaid gemstone eyes, Ch 7, [98–127] (many types & examples); gemstones in general, Ch 16, [386–405]; other stones, Ch 17, [406–28]. Lucas should always be consulted whenever one writes or lectures about Egyptian jewelry.

corundum, gems