Figure 15. This ternary diagram for jadeite (Jd)-aegirine + kosmochlor (Ae + Ko)-Ca-Fe-Mg pyroxene (diopside + augite + hedenbergite) indicates the chemical concentration data of four green jadeites from Itoigawa-Omi by EPMA, based on Morimoto et al. (1988). Their compositions fit the jadeite range of XJd = 98.7 to 82.4. Three to 12 spots were tested on the green area of each specimen.
Figure 14. This classification of pyroxene based on chemical composition shows the relationship between jadeite and other pyroxenes in the main isomorphous substitution. Source: National Museum of Nature and Science, Tokyo.
Figure 13. A: The UV-Vis spectrum of a green Burmese jadeite (K-MYA-16) shows the characteristic chromium lines at 630, 650, and 691 nm and the sharp, narrow Fe3+ absorption band at 437 nm that is commonly seen in natural green jadeite. The Cr3+- and Fe3+-related feature generally overlaps with the spectrum of Japanese green jadeite, but the absorption intensity is much higher due to its color saturation and transparency. B: Burmese lavender jadeite (K-MYA-20) showed a dominant broad absorption band centered at 570 nm, related to Mn3+ concentration. C: The narrow Fe3+ absorption band at 437 nm, often present in Guatemalan green jadeite (M-GUA-02). The absorption of Cr3+ is not detectable in this 2.32-mm-thick sample. D: The spectrum of Guatemalan lavender jadeite (M-GUA-03) shows multiple broad bands centered at 530 and 610 nm and a weak narrow band at 437 nm. The absorption feature related to Mn3+, Ti4+-Fe2+, and Fe3+ generally overlaps with the bands observed in Itoigawa lavender jadeite. E: A vivid green Polar Ural jadeite shows an Fe3+ band and strong multiple chromium lines in the 580–700 nm range, a combination that typically produces a highly saturated green color. The concentration of Cr (maximum of 3042 ppma) is much higher than in Japanese green jadeite.
Figure 12. The UV-Vis spectrum of a blue sample from Itoigawa (K-IT-JP-16). The absorption shows a very wide broad band from 500 to 750 nm that overlaps the Mn-related broad bands at 530 and 570 nm observed in Burmese lavender jadeite. The chromophores Ti and Fe show a significant concentration at 1943 and 4212 ppma, respectively, and this jadeite’s blue color could be mainly due to the Ti4+-Fe2+ charge transfer.
Figure 11. Illustration of the atomic arrangement of a single-chain pyroxene crystal structure, from the a-axis to b-axis direction. In the SiO4 tetrahedrons (indicated in yellow and brown), four oxygen atoms surrounding a silicon atom are connected to form a strand, and other six-coordinate octahedron atoms (in green) are arranged so that they link the strands. Larger atoms (orange spheres) fill the spaces. Modified after Miyawaki (2004).
Figure 10. The UV-Vis spectrum of a lavender sample from Itoigawa-Omi (K-IT-JP-25). Two broad bands centered at 530 and 610 nm correspond to Mn and Ti-Fe charge transfer, and there is also a weak narrow band at 437 nm. The violet color reflects the chromophore combination of low Mn (18 ppma) and much higher Ti (534 ppma) and Fe (550 ppma).
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