Lepidolite in Copper-Bearing Tourmaline
The author recently examined a 0.53 ct copper-bearing tourmaline with a well-formed transparent crystal (see above). Raman spectroscopy identified the crystal as lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2), a member of the mica group. Lepidolite frequently occurs alongside tourmaline but is usually seen in lower-quality stones or collector specimens. Typical inclusions observed in gem-quality tourmalines include tubules, fine needles, and fluid inclusions. Lepidolite crystals in tourmaline have been observed in stones from multiple localities, so such an inclusion is not an indicator of geographic origin. Due to the preference of less included stones in jewelry, it is rare to encounter a sizeable, well-formed crystal in a faceted gem-quality tourmaline.
