Micro-World Gems & Gemology, Summer 2022, Vol. 58, No. 2

Blue Apatite in Tanzanian Garnet

Needles surround blue apatite crystals in a Tanzanian 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.

E. Billie Hughes is a gemologist and co-founder of Lotus Gemology in Bangkok.