FMF - Friends of Minerals Forum, discussion and message board

[BridgetownTreasures]

Hi all - I have this piece of tourmaline from Northern California and I’m struggling to find the specific variety. It is pink-to-purple, with a lot of rainbow/iridescent refractions throughout.

Are there specific tests that will narrow down more than just “tourmaline”

Thanks for your patience with a beginner!

[Pete Richards]

Most probably it's elbaite, given the color and California. Can you be more specific about where in Northern California it came from, and how you got it?

There are tests that can be done to determine the chemical composition, which defines the kind of tourmaline, but they are not cheap and it might be hard to find someone who could do them for you. Locality may be the best indicator.

[BridgetownTreasures]

Thank you!

As I look at grandpa's chicken scratch (This piece came to me through a gorgeous collection I inherited - unfortunately the labeling is not good), there are two tourmaline entries. One says "N. Calif" and the other says "Mesa Grande". There is only one piece of tourmaline, so I'm not 100% sure which locale it is, which I know limits ID efforts.

Thank you again - I know that you are limited by my lack of info - even broad "musings" are if interest to me!

[Jesse Fisher]

There are few, if any locations for colored tourmaline (most likely elbaite) in Northern California. Mesa Grande, which is in San Diego County, is the location of the Himalaya Mine, which along with the nearby Pala District was a prolific source of the mineral for much of the 20th century.

[basti]

The pink tourmaline is very likely elbaite or fluor-elbaite, pink tourmaline is labeled as variety rubellite. I have some analyses from Victor, Caterina, Himalaya and Stewart - all are elbaites.

The green layer outside on the pink tourmies is often very close to the border between lithium-rich schorl or iron-rich elbaite. Green variety is labeled as verdelite.

Finding precise locality based on geochemistry of tourmaline chunk alone is very difficult. They are very similar and many localities contain several lithium-turmaline generations.

For advanced collectors: Pink rubellite can be also darrellhenryite, rossmanite and couple other tourmalines - not sure if these were found in California so far. Also some schorls and less often dravites can be green, but these do not usually form in the LCT pegmatite core.