Jadeite images and spectra

Well, this was one of the hardest ones for me to identify; partly because I was not aware that I had any jadeite in my collection of crystals and gemstones. To start with, I could not find any fluorescence spectra on the web so I was left with a measurement (red line) that appeared to be from the chromium ion Cr^3+ - like ruby, spinel, kyanite, topaz etc. - but with a detailed character that was not described. In the end, I found an absorbance spectrum of jadeite in an advert for a Swiss gemmological spectrophotometer system.

Jadeite is a sodium aluminium silicate Na Al (Si O_3)_2. The marked absorption between 430 and 440nm is due to iron and the feature at 692nm is due to chromium. The wavelengths of these features clearly identify the sample. The fluorescence includes a broad band extending from 550 to 650nm that results in an orange luminescence rather than the more usual red colour from chromium.
The top right of the composite figure shows a white-light photograph of my sample which is about 20 x 8 mm in size. The colour is a pale green-blue and this crystal is quite transparent rather than the more common translucence of jadeite. The two images at the bottom show one end of the crystal being illuminated with my 404nm laser producing a rather weak orange glow. The right-hand image has some additional white light illumination but both are photographed through a yellow filter to remove the scattered blue laser light.

My luminescence spectrum is the only one I can find on the web. If you know of any other, please drop me an email.

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