corundum, inclusions.5, gems

Sorby’s landmark paper demonstrates how microscopic examination of minerals and rocks can be used to reconstruct the conditions under which they formed. Using thin sections and transmitted-light microscopy, he studies crystal textures and, especially, microscopic cavities and fluid inclusions containing liquids, gases, and sometimes daughter crystals. Sorby shows that such inclusions may preserve samples of the fluids present during crystal growth and that changes in their liquid and vapor proportions upon heating can provide information on formation temperatures. From these observations he distinguishes minerals formed from aqueous solutions, molten material, and other geological environments and applies the method to interpreting the origin of rocks. The paper is foundational to microscopic petrography and fluid-inclusion research and is particularly important to gemology because the study of inclusions subsequently became one of the principal means of determining gemstone genesis, geological environment, and, ultimately, distinguishing natural from synthetic and treated gems.

corundum, sapphire, inclusions.5, gems

A brief note by David Brewster reporting a large fluid-filled cavity observed in a specimen of sapphire. The paper extends his earlier investigations of fluids enclosed within minerals and records the presence and behavior of the trapped liquid in corundum. Of particular gemological importance, it is an early specific description of a fluid inclusion in sapphire, demonstrating that such inclusions occur in precious stones as well as in other minerals. The notice forms part of Brewster’s pioneering work on mineral inclusions and the physical conditions under which crystals form.

corundum, inclusions.5, gems

An important early study by Humphry Davy of fluid and gaseous inclusions enclosed within crystals. Davy examines cavities containing liquid and aeriform matter in several minerals and considers the physical state, composition and behavior of the enclosed substances when the crystals are heated or broken. The paper is significant in the history of mineralogy because it helped establish that crystals can trap fluids and gases during their formation, providing evidence about the conditions under which minerals crystallize. For gemology, it is an early contribution to the study of fluid inclusions, which later became important for understanding gemstone genesis, geological environment and, in some cases, geographic origin.

gems, jade, Fischer-Book, mineralogy, early mineralogy

Very scarce. Edited by Bartolomeo Ambrosini [see note below]. Some forty years after he died, Aldrovandi's Musaeum Metallicum was published as a thick folio volume. Since his death, the work had existed as a manuscript, Geologica ovvero Fossilibus" in the library collections of the University of Bologna, which had been bequeathed all of Aldrovandi's manuscripts. Even unpublished, many scholars studied it as a resource for their own researches. The value others placed upon Aldrovandi's material did not go unnoticed, which is why a former student of the author, Bartolomeo Ambrosini was entrusted by the Bologna senate to edit the material Aldrovandi had accumulated and oversee its publication. The final product is a superb book. The work consists of a single volume divided into four books: on metals, earths, succi concreti (concrete juices), and stones (minerals, rocks, and fossils). Within each of these books, whole chapters are devoted to the consideration of a single "fossil." In a style typical of its time, each chapter then describes the fossil's medical properties, synonyms, localities, origins, varieties, and uses. Aldrovandi includes references to classical and medival authors through out the volume in a fashion that anticipated modern scholars by compiling long lists of authorities but omitting those commonly cited (Partington, 1961-70). The antiquarian nature of the book commonly gives the names and descriptions of the items listed a strange, unrecognizable character. However, Foresti (1887) attempted to ease the struggle by matching relatively modern names to Aldrovandi's. The comprehensive index included at the end of Musaeum Metallicum also makes this a reader friendly book. Perhaps the most outstanding feature for the connoiseur of mineralogic literature are the several hundered woodcuts scattered throughout the volume. Some of these are full page but most are smaller, with many possessing a quaint, interesting character. These figures are designed to illustrate features described in the text, but since minerals do not easily lend themselves to illustration, the pictures "rather require the text to explain them" (Adams, 1938). That Aldrovandi was a man of accumulation is clearly shown by his inclusion of all facts that came to his attention without apparently any critical faculty to distinguish between the true and imaginary, the important and nonessential. A great amount of scientific value is contained in Musaeum Metallicum but an overburden must be removed to discover those nuggets. In truth, the author was a product of his time. The influence of the church and other authorities did not bind his writings and ideas as they had past authors, "and so," as Adams (1938) writes, "one gathers the impression that he was writing at the opening of a new age ...""

corundum, history.1, India.12, gems, Indian lapidary

Sinkankas: This work presents translations of chapters 68–80 of the Sanskrit Garuḍa Purāṇa, which “elaborately describes the supernatural origin of gems and their mineralogical properties,” along with the Graha-cocāra Jyautiṣa, a text that “gives complete information on the astrological characteristics and effects of the principal gemstones” and “explains how auspicious gems help remove obstructions in various areas of life by appeasing planets that are having unfavorable effects.” The first thirteen chapters focus on planetary gemstones, offering summary translations of relevant Garuḍa Purāṇa passages concerning ruby, pearl, yellow sapphire, hessonite, emerald, diamond, cat’s-eye chrysoberyl, blue sapphire, coral, red garnet, jade (including jadeite), rock crystal, and bloodstone. Secondary planetary gemstones, or uparatnas, such as red spinel, moonstone, yellow topaz, citrine, hyacinth, peridot, tsavorite, green tourmaline, white zircon, turquoise, goshenite, amethyst, apatite cat’s-eye, blue spinel, tanzanite, lapis lazuli, and carnelian, are not directly traced to specific textual sources, and some—like tsavorite, goshenite, and tanzanite—were unknown to the ancients, suggesting these may have been included at the authors’ discretion. Each gemstone description includes its properties and modern sources, and although there is no bibliography, a valuable feature of the work is its inclusion of alternative Sanskrit names for the gemstones.

gems, corundum, Vietnam.12, geology.11, Cenozoic basalt, Sapphire, Southern Vietnam, U-Pb, Zircon

Trace element geochemistry of zircon inclusion in sapphire from Southern Vietnam shows a large variation in Hf (1.1 to 2.7 wt%), Y (779 – 4220 ppm), Th (329 – 5199 ppm), U (224 – 3587 ppm), and ∑REE (706 – 2710 ppm) abundances with clearly positive Ce and mildly negative Eu anomalies observed in chondrite-normalized REE patterns. These characteristics suggest that the majority of the host sapphires were crystallized from evolved felsic melt at the lower crustal levels. The U-Pb zircon dating yields the ages ranging between 35.5 ± 1.6 Ma and 14.7 ± 0.29 Ma for Krong Nang sapphire, 5.9 ± 0.13 Ma for Binh Thuan sapphire, 5.6 ± 0.07 Ma for Dak Nong sapphire, and 5.5 ± 0.08 Ma for Di Linh sapphire. Except the Krong Nang sapphire, these ages are coeval with the alkali basalt eruptions in Southern Vietnam. This implies the crystallization of sapphire during early stages of the basaltic magmatism. Sapphire and associated minerals were extensively transported from different depths to the surface during the later stages of basalt magmatism (≤5 Ma).

gems, spinel, emerald, alexandrite, Malysheva, Mariinsky deposit, Ural’s emerald mines, geochemical features, optical spectroscopy, Bazhenov ophiolite complex, Russia, inclusions, beryl, chrysoberyl, chromophores, geology

The distribution of chromophores and the composition of the chromium-bearing spinels in Uralian emeralds and alexandrites were studied for the first time. It was proved the main source of chromium for the coloring of emeralds and alexandrites from the Mariinsky deposit was the chromium-bearing spinels of the Bazhenov ophiolite complex. The rare mineral zincochromite is described as an inclusion in the Uralian emeralds for the first time.

gems, jade, nephrite, Xinjiang, Chinese jade, Khotan, inclusions, zircon dating

The Omixia nephrite deposit, situated in the central West Kunlun Orogenic Belt, is hosted in Mg-skarn formed between granite and magnesian marble. Despite its large size and extensive exploration, the ore genesis and precise age of the deposit have remained poorly understood. This study aims to clarify the genesis and constrain the upper age of the deposit through petrological analysis and LA-ICP-MS U-Pb zircon dating. Petrographic observations reveal that nephrite formed in multiple stages, including tremolite mineralization, diapolitization, fine granulation, and recrystallization. Geochemically, the nephrite displays low total rare earth element (ΣREE) content, averaging 7.228 μg/g, with strongly negative Eu anomalies (δEu = 0.58–0.73), declined light REE patterns, and flat heavy REE patterns. U-Pb zircon ages in the nephrite range from 489.6 ± 10.5 Ma to 411.1 ± 5.3 Ma, indicating formation during the Late Caledonian to Early Hercynian periods. These findings confirm that the Omixia deposit is a typical contact metasomatic Mg-skarn nephrite deposit, and they provide valuable insights into the genesis of nephrite in the West Kunlun region of Xinjiang, contributing foundational data for further geological research in the area.

gems, corundum, treatments.6

Stephan and Müller examine methods for identifying heat treatment in corundum, with particular emphasis on ruby and sapphire. The article reviews the effects of heating on internal features and gemological properties and discusses the diagnostic evidence that can distinguish heated from unheated stones. Microscopic criteria include changes to mineral inclusions, healed fissures, altered growth structures, and other heat-related features, while spectroscopic and analytical methods provide additional evidence where microscopy alone is inconclusive. The authors consider the difficulties created by different heating temperatures, treatment conditions, and starting materials, since some treatments produce conspicuous alteration whereas others leave only subtle indications. The study emphasizes the need to combine microscopic observation with appropriate instrumental methods when determining whether a ruby or sapphire has undergone heat treatment.

gems, corundum, inclusions.5, E. Billie Hughes, Lotus Gemology

Today women are playing an integral role in the jewellery and gemstone industry from the store front to the laboratory. Here we look at the women who are making a difference.