Search

Obi Island is a small, remote Indonesian island located in the Molucca Sea that is endowed with a variety of mineral resources. Since 2019, artisanal miners have produced colourful specimens containing various copper minerals in chalcedony from altered andesite breccia near the village of Sesepe in the north-eastern part of the island. The specimens are sawn open to reveal the copper mineralisation, and sold into the lapidary and collector market. Locals call this material batu kawat, meaning 'wire rock'. Silica-rich areas of the deposit provide semi-transparent masses of chalcedony that are speckled with blue chrysocolla and shiny blebs of native copper (e.g. 'confetti chrysocolla'). The combination of interesting textures and attractive colouration make these ornamental materials popular with collectors and lapidaries. [ABSTRACT FROM AUTHOR]

Gem-quality pink-orange euclase was discovered in Bahia, Brazil, in 2015-2016, but did not enter the international gem and mineral trade until mid-2018. There has been limited production to date from two different occurrences, located about 30 km apart, with an estimated production of less than 1 kg total from both sources. Although the pink-orange euclase from each occurrence has distinctive internal features, crystal morphology and colour zoning--allowing rough or cut stones from each locality to be readily separated from one another--their gemmological and chemical properties are similar, indicating they probably formed in a similar geological context. Some notable internal features exhibited by samples from the second reported occurrence include curly/woolly 'fibres' and associated circular/cylindrical inclusions. The unusual pink-orange colouration of this euclase is due to traces of Mn3+. [ABSTRACT FROM AUTHOR]

This article discusses the discovery of a new type of silicified wood from Sumatra, Indonesia, which was showcased at the Tucson gem shows in February 2024. The wood, known as "drusy pocket" petrified wood, is characterized by voids lined with tiny quartz crystals and banded grey-to-white fillings resembling agate or chalcedony. The matrix material can be heat-treated to create an attractive orange to red-brown color. The article also mentions the use of statistical processing and spectroscopic and chemical analyses to determine the geographic origin of high-quality green jadeite-omphacite jade from Myanmar, Guatemala, and Italy. [Extracted from the article]

This article from the Journal of Gemmology discusses two different gemstones. The first is cleavelandite, a platy variety of albite, which is commonly found in granitic pegmatites in Maine, USA. The author describes a rare instance of a faceted cleavelandite crystal, which exhibited a pale blue color and moderate red fluorescence under UV radiation. The second gemstone discussed is azurite, a blue copper-ore mineral. The authors obtained rough azurite specimens from the Kamenushinskoe deposit in Russia and fashioned them into cabochons. The cabochons displayed a deep blue color and were confirmed as azurite through Raman spectroscopy. [Extracted from the article]

This article discusses the additional production of rainbow moonstone feldspar from Madagascar. Rainbow moonstone is a type of plagioclase with a composition near the andesine/labradorite border, known for its labradorescence and adularescence. The high-quality and transparent rainbow moonstone from Madagascar can now be cut into faceted stones. The mining area is located near the village of Tsarantanana, and production is ongoing, although it is becoming rare to find clean pieces in larger sizes. The article provides detailed characterization of the rainbow moonstone, including its composition, physical properties, and spectroscopic analysis. [Extracted from the article]

The 2024 Accredited Gemologists Association (AGA) Conference in Tucson, Arizona marked the 50th anniversary of AGA and was the best-attended conference in its history, with 145 people from 17 countries in attendance. The conference featured six invited presenters, including updates on ongoing research on fancy-shape diamond cuts, the discovery of a pearl from a Saccostrea cuccullata oyster in Bahrain, and the examination of blue sapphires from Myanmar. Other presentations covered the history and recent developments of mineral and gem research, the history of gem cutting, and a behind-the-scenes tour of the Smithsonian National Museum of Natural History. The conference concluded with the AGA Gala, where Dr. Jeffrey Post received the 2023 Antonio C. Bonanno Award for Excellence in Gemology. [Extracted from the article]

This article discusses the occurrence of wulfenite, a secondary mineral, in Namibia. Wulfenite is typically colorless to yellow, orange, or red and is prized by mineral collectors. Although it is not commonly used as a gemstone due to its crystal structure and hardness, faceted wulfenite gemstones were recently available at the Tucson gem shows. The article also briefly mentions the discovery of xonotlite, a calcium silicate hydroxide, as a gemstone in Italy. [Extracted from the article]

This article from the Journal of Gemmology discusses scheelite, a collector's stone that forms a solid-solution series with powellite. The article focuses on scheelite from Namibia, which was displayed at the February 2024 Tucson gem shows. The author compares the UV fluorescence behavior of scheelite from Namibia with scheelite from Kern County, California, noting that the Namibian scheelite fluoresced yellow to long-wave UV radiation, while the samples from the USA were inert. The article also provides information about the origin of the Namibian scheelite and mentions that new production of scheelite gemstones from this locality is unlikely in the near future. [Extracted from the article]

This article from the Journal of Gemmology discusses iolite gemstones from Tanzania that contain large hematite inclusions. These inclusions create an iridescent effect when the stones are viewed in a specific orientation. The iolite with hematite inclusions is referred to as "iolite sunstone" and is a unique addition to gem materials that exhibit aventurescence or spangled optical effects. The article also mentions the identification of two pale blue gemstones that were initially thought to be Paraíba tourmaline but were later identified as montebrasite. [Extracted from the article]

This article from the Journal of Gemmology discusses the presence of cassiterite, an important tin ore mineral, in Namibia. The mineral is found in granitic pegmatites and related greisens in the central Namibian region. While most cassiterite is black and opaque, gem-quality material is rare. The article highlights the discovery of impressive cassiterite gemstones from Namibia, including a 37.74-carat stone that is notable for its size and transparency. Similar gem-quality cassiterite is known from China, but the stones from Namibia stand out for their larger size. [Extracted from the article]

Jadeite traders often attempt to judge the internal quality of alluvial jadeite based on characteristics of this crust, with certain features such as a waxy appearance suggestive of valuable rough material. While this isn't the first time that synthetic forsterite has been faceted for gem use (Nassau 1994 illustrated a cut, light blue Cr-doped synthetic forsterite), it might the first time that colourless material has been faceted. The synthetic tephroite displays a deep pink-red colour similar to that of some rhodochrosite (also coloured by Mn), while the pure end-member forsterite contains no Fe or Mn and is therefore colourless. [Extracted from the article]

Gem-quality rhodochrosite is rarely encountered, and is here described and characterised from the few known localities in the USA (Colorado), China, South Africa, Peru, Argentina and Brazil. The gemstones examined for this study were all relatively clean, with the main internal features consisting of partially healed fissures and two- and three-phase inclusions. Generally, rhodochrosite from China showed the most visible internal features, whereas the samples from South Africa showed peculiar growth-zoning patterns, which can be related to the distinctive crystal habits of material from this locality. A reconnaissance study of the chemical composition of a few samples from each locality showed that the South African stones were the purest rhodochrosite, with low Mg and very low Ca and Fe. The Brazilian material showed the highest Fe content, along with very low Mg, while rhodochrosite from China showed greater Mg but low Ca. Elevated traces of Pb, Y and heavy REEs were found in rhodochrosite from Colorado. [ABSTRACT FROM AUTHOR]