Typical tourmaline removed from pocket 28. The
red portions of some of these tourmalines are rossmanite.
Photo courtesy of Gary Freeman, Coromoto Minerals.
Analyses at the University of New Orleans have shown that portions of elbaite crystals that occur at Mount Mica, Maine, grade into rossmanite. The analyzed crystals occured in pocket 28, discovered in 2004. Most tourmaline from this pocked is elbaite. The black caps are foitite and directly under the foitite caps is where the rossmanite is usually found. A couple of red crystals contain zones of rossmanite composition (Hedegaard 2005).
Analyses courtesy of Skip Simmons, University of New Orleans
Comparison to Elba, Italy
Some of the Mt Mica crystals have a black cap of foitite similar to the black foitite cap on elbaite-rossmanite from Elba, Italy. The region on the crystal under the black foitite cap is where the rossmanite occurs at both localities.
Mt Mica tourmaline
Freeman, Gary (2005) personal communication.
Hedegaard C (2005) Tucson 2005 - green rocks galore.
Simmons B, laurs BM, Falster AU, Koivula JI, Webber KL (2005) MT. Mica: A renaissance in Maine's gem tourmaline production. Gems & Gemology 41, 150-163.