摘要
The author studied how to distinguish Omphacite from Jadeite through using basic gemmologicalmethods such as visual observation,R.I.,S.G.,microscopic method,and also pertographic study throughthin sections together with XRD,UV-vis—NIR spectrophotometry,and FTIR methods.The preliminaryconclusion is:in order to distinguish jadeite from omphacite one could use visual observation:omphacite isdark to very dark green to opaque whereas jadeite can be colourless to pale or bright green;RI:omphacite is 1.68to 1.72 whereas jadeite is 1.65 to 1.67;SG:omphacite is 3.35 to 3.40 whereas jadeite is 3.33 to 3.36;and EDAX:jadeite should contain more than 80%Na compared to Ca,and more than 80%or 50%A1 compared to Mg+Fe2+ or to Fe3+ respectively.Any chemical compositions departing from this should not be called jadeite.