Figure 9. The UV-Vis spectrum of a green sample from Itoigawa (K-IT-JP-14) shows the features corresponding to Cr- and Fe-bearing green jadeite: the characteristic narrow 691 nm absorption, two Cr3+-related weak shoulders at 650 and 630 nm, and a sharp, narrow absorption of Fe3+ at 437 nm. The saturated green area of the spectrum corresponds to the concentration of the chromophores Cr and Fe (280 and 810 ppma, on average).
Figure 8. A two-dimensional Raman spectroscopy mapping image of a jadeite boulder from Itoigawa. The red area corresponds to the jadeite distribution, the green area to dark green richterite (amphibole group), and the blue area to the mineral prehnite, which is located at the veinlet and crosses through the stone. The mapping area is 44 × 30 mm.
Figure 7. Petrographic microscope images of jadeite samples from Itoigawa. The left images are under plane-polarized light, the right images under cross-polarized light. Jd, Preh, Ves, An, and Ti indicate jadeite, prehnite, vesuvianite, analcime, and titanite, respectively. A1: Green jadeite K-IT-JP-14 shows a prismatic-granular crystalloblastic texture, a distribution of fine colorless cryptocrystalline grains of jadeite, and a predominance of grains around 0.05–0.3 mm in size. A2: Coarse pale green grains larger than 2 mm can also be observed in the same matrix, which is a well-formed large jadeite single crystal. The prominent (110) cleavage planes intersecting at 87° are characteristic of pyroxene. B1: Lavender jadeite K-IT-JP-25 shows near-colorless fine and micro-grained jadeite crystals with a prismatic crystalloblastic texture. B2: Ultramylonitic zones with radiating aggregates of fine jadeite grains cut randomly through the center of the matrix, indicating a lithostatic pressure during the metamorphic process. B3: Dark gray prehnite and analcime, the main constituents of the veinlets that cut through this lavender jadeite, were formed by hydrothermal fluids. A high-relief prismatic vesuvianite crystal was also found as a component mineral. C1: K-IT-JP-16 is a predominantly blue specimen, translucent with fine cryptocrystalline grains. C2: Crushed preexisting minerals produce a flow structure with granoblastic and mylonitic texture. The component minerals analcime and a very minor amount of euhedral titanite grains are observed in the matrix. Photomicrographs by Ahmadjan Abduriyim.
Figure 6. Left: A 4.6 ton jadeite rough boulder is displayed at the Fossa Magna Museum in Itoigawa. This eroded and rounded boulder from the Kotaki area is mostly white, with some green areas of jadeite; the fibrous structure in the black area is amphibole. Thin fault-like veins are filled with white minerals. Center: A 30 kg rounded boulder of predominantly lavender jadeite was found along the Hime River in Itoigawa. The lavender color is dispersed irregularly over the white matrix. Right: These rounded jadeite pebbles, found along the coast in Itoigawa-Omi, are approximately 2 to 15 cm long. Photos by Ahmadjan Abduriyim, courtesy of the Fossa Magna Museum and the Jade Ore Museum (Hisui Gensekikan).
Figure 7. Petrographic microscope images of jadeite samples from Itoigawa. The left images are under plane-polarized light, the right images under cross-polarized light. Jd, Preh, Ves, An, and Ti indicate jadeite, prehnite, vesuvianite, analcime, and titanite, respectively. A1: Green jadeite K-IT-JP-14 shows a prismatic-granular crystalloblastic texture, a distribution of fine colorless cryptocrystalline grains of jadeite, and a predominance of grains around 0.05–0.3 mm in size. A2: Coarse pale green grains larger than 2 mm can also be observed in the same matrix, which is a well-formed large jadeite single crystal. The prominent (110) cleavage planes intersecting at 87° are characteristic of pyroxene. B1: Lavender jadeite K-IT-JP-25 shows near-colorless fine and micro-grained jadeite crystals with a prismatic crystalloblastic texture. B2: Ultramylonitic zones with radiating aggregates of fine jadeite grains cut randomly through the center of the matrix, indicating a lithostatic pressure during the metamorphic process. B3: Dark gray prehnite and analcime, the main constituents of the veinlets that cut through this lavender jadeite, were formed by hydrothermal fluids. A high-relief prismatic vesuvianite crystal was also found as a component mineral. C1: K-IT-JP-16 is a predominantly blue specimen, translucent with fine cryptocrystalline grains. C2: Crushed preexisting minerals produce a flow structure with granoblastic and mylonitic texture. The component minerals analcime and a very minor amount of euhedral titanite grains are observed in the matrix. Photomicrographs by Ahmadjan Abduriyim.
Figure 4. Jadeite from Itoigawa is found in serpentinite along a fault as blocks near the Kotaki River (upstream of the Hime River) and the Omi River. The Kotaki and Hashidate valleys are the main sources of gem-quality jadeite. White is the most common color, followed by green. Lavender, violet-blue, and blue jadeite are also found in Itoigawa-Omi. Source: Fossa Magna Museum.
Figure 5. Representative samples from four locations. A: Magatama carvings (25.51–63.88 ct) from Itoigawa-Omi. B: Variously colored rough jadeite boulder, cobble, and pebbles from Itoigawa-Omi (15.3–622.2 g) and a polished violetish blue jadeite from the Wakasa region (458.2 g). C: Green and lavender cabochons (4.75–15.45 ct) and polished slices from Kachin, Myanmar (17.84–136.4 g). D: Rough grayish green and lavender jadeite blocks from the Motagua region of Guatemala (223–1250 g). E: A green jadeite block (304 g) and two polished translucent to opaque jadeites (139.08 and 5.93 ct) from the Polar Urals of Russia. The magatama from Itoigawa-Omi and the Russian and Guatemalan samples are courtesy of the Jade Ore Museum (Hisui Gensekikan). The Burmese jadeites are courtesy of Miyuki Co., Ltd. Photos by Masumi Saito and Ahmadjan Abduriyim.
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