Blue apatite crystals in garnet.
Blue apatite crystals are beautifully framed by prominent rutile needles in a garnet from Tanzania. Photomicrograph by E. Billie Hughes; field of view 3.5 mm.
In the micro-world, it can be challenging to identify inclusions based on sight alone, as many minerals can have a similar appearance. Occasionally, though, some inclusions have characteristic features that can aid in their identification.
Recently this author had the opportunity to observe a pyrope-spessartine garnet, reportedly from Lindi Province, Tanzania, that contained blue crystal inclusions ensconced among intersecting needles (see above). Analysis with micro-Raman spectroscopy identified the inclusions as apatite. Apatites are known for their bright blue hues, and these inclusions offered an attractive example.
While this sample hails from Tanzania, blue apatite has previously been reported as an inclusion in garnet from Madagascar (Winter 2020 G&G Micro-World, p. 526). These inclusions’ distinctive appearance may help gemologists recognize the material in other samples, but further analysis should be performed to identify them definitively.
About the Author
E. Billie Hughes visited her first gem mine (in Thailand) at age two and by age four had visited three major sapphire localities in Montana. A 2011 graduate of UCLA, she qualified as a Fellow of the Gemmological Association of Great Britain (FGA) in 2013. An award winning photographer and photomicrographer, she has won prizes in the Nikon Small World and Gem-A competitions, among others. Her writing and images have been featured in books, magazines, and online by Forbes, Vogue, National Geographic, and more. In 2019 the Accredited Gemologists Association awarded her their Gemological Research Grant. Billie is a sought-after lecturer and has spoken around the world to groups including Cartier and Van Cleef & Arpels. In 2020 Van Cleef & Arpels’ L’École School of Jewellery Arts staged exhibitions of her photomicrographs in Paris and Hong Kong.
Acknowledgements
Specimen courtesy of Mark Saul. Fabrication courtesy of Indy Khurana.
Notes
This article first appeared in Gems & Gemology, Fall 2021, Vol. 57, No. 3, p. 268.