The Study On Gemological And Mineralogical Characteristics Of Guatemala Green Feicui

In Guatemala, jadeitite occurs as blocks in Cretaceous serpentinite mélange in distinct settings on opposite sides of the Motagua fault, the boundary between the North American and Caribbean plates. Jadeitites north of the Motagua fault are distributed over a 200 km E-W area. Lithologies, P-T conditions and chronology on either side of the Motagua fault, with the exception of the serpentinites and related rocks, are different from each other.In this paper, green feicui samples collected from Guatemala, including blue-green, dark green and light grayish green, were studied by normal Gemmological testing, optical microscopy(OM), Cathodoluminescence(CL), Electron probe analysis(EP), X-ray powder diffraction(XRD), Uv-vis spectrum and infrared spectroscopy(IR) on their basic gemology mineral composition, chemical composition, texture, spectral characteristics and coloring elements.Blue-green feicui: greasy to vitreous luster; translucent; refractive index is 1.66; the relative density of 3.22-3.31; porphyroblastic texture and mylonitic texture; mineral compositions are jadeite, omphacite, and a small amount of phengite, allanite, titanite, zircon and rutile.Light grayish green feicui: greasy to vitreous luster; opaque; refractive index measurement is 1.67-1.68; the relative density is 3.26-3.30; visible " Cleavage flash"; cataclastic structure and prismatic granular mosaic texture; mineral compositions are jadeite, and a small amount of biotite and clinozoisite.Dark green jade: vitreous luster; translucent; refractive index measurement is 1.66; the relative density of 3.27-3.34; Micro-crystalloblastic texture and mylonitic texture; mineral compositions are jadeite, omphacite and a small amount of garnet.The IR of blue-green feicui mainly showed characteristic peaks of jadeite, the main peak is 1081 cm-1, 954 cm-1, 582 cm-1, 524 cm-1, 470 cm-1, 435cm-1. Light grayish green feicui showed characteristic peaks of jadeite representatively, the main peak is 1086 cm-1, 954 cm-1, 590 cm-1, 534 cm-1, 522 cm-1, 471 cm-1, 435 cm-1. Dark green feicui mainly display infrared spectra of omphacite, the main peak is 1064cm-1, 961 cm-1, 562 cm-1, 521 cm-1, 455 cm-1, 441 cm-1.The UV-vis spectra of blue-green and light grayish green feicui shows 434 nm line. Dark green feicui shows 436 nm line and chromium-related bands at about 693 nm, 670 nm, 656 nm, which cause a pure green color in transmitted light.