Tourmaline in Emerald
Prismatic black tourmaline in a Zambian emerald. Photomicrograph by Virginia Schneider; field of view 1.76 mm.
The author recently examined a 3.80 ct emerald with well-formed black, opaque prismatic crystals (see above). The surface-reaching crystals were identified as tourmaline through the use of Raman spectroscopy. While tourmaline crystals are relatively uncommon inclusions, they have been documented in emeralds from Zambia, Pakistan, Russia, and Ethiopia, all of which are schist-hosted deposits. Laser ablation–inductively coupled plasma–mass spectrometry chemical analysis combined with inclusion observation revealed this emerald to be of Zambian origin.
