The Study On Gemological And Mineralogical Of Guatemala Jadeitites With Albite

Jadeitite,a type of rock composed principally of jadeite.There were nearly 30 jadeitite deposits which were discovered in the world.Jadeitite is almost forms under a relatively high-P/low-T condition in the subduction zones.And it also has the great significance of searching the jadeitite resource.The Guatemala jadeitite deposits was discovered in the Motagua River of Motagua fault zone.The research of Myanmar jadeitite have attracted much attention from geologists and gemologists internationally.However,there has been little understanding about the Guatemala jadeitite.In this paper,jadeitite samples collected from Guatemala,including jadeitite,albite-jadeitite and omphacite-jadeitite,were studied by normal Gemological testing,optical microscopy,Electron probe Microanalysis（EPMA）,X-ray powder diffraction（XRD）,Infrared spectroscopy（IR）,Raman spectrum and Uv-vis-NIR spectrum on their basic gemology mineral composition,chemical composition,texture and spectral characteristics.Petrological and mineralogical studies show that the characteristics of jadeitite from Guatemala are described as follows:The jadeitite shows granular and catalastic texture,and jadeite is carved by albite veins;Albite-jadeitite shows that replacement of the jadeite by albite in albite-jadeitite along its cleavage and crack;And omphacite-jadeitite show micro-crystalloblastic texture,and the early jadeite and omphacite are carved by later jadeite and omphacite veins.Mineral composition of jadeitite are jadeite,with few amount of albite and biotite.Mineral composition of albite-jadeitite are jadeite and albite,few amount of albite and biotite,with few amount of omphacite,phengite and quartz.Mineral composition of omphacite-jadeitite are jadeite and omphacite,with few amount of albite,biotite and titanite.The IR spectrum showed that jadeitite of Guatemala has the characteristic IR peaks of jadeite;Albite-jadeitite has the characteristic IR peaks of albite and jadeite;omphacite-jadeitite has the characteristic IR peaks similar with jadeite,and however,some peaks are deviant to low frequency.The Raman spectrum showed that jadeitite of Guatemala has the characteristic Raman peaks of jadeite;Albite-jadeitite has the characteristic Raman peaks of albite and jadeite;omphacite-jadeitite has the characteristic Raman peaks of omphacite plus jadeite,and however,parts of peaks are deviant to low frequency.The Uv-vis-NIR spectrum showed that jadeitite and albite-jadeitite of Guatemala has the 435.5nm line.This line caused by Fe³⁺.And omphacite-jadeitite didn’t has the line of 435.5.Considering the petrology and mineralogy of jadeitite from Guatemala,we can conclude that the gemmological significance by discuss on considering the mineral composition and structure.