The origin of color in tourmaline from Mt. Marie, Maine

In September and December 2010, Dennis Durgin sent this author two fragments of recently mined Mt. Marie tourmaline for color-origin investigation. The samples were yellowish green (GRR 2016, 19 x 12 x 9 mm) and dark blue (GRR 2924, 15 x 15 x 6 mm). The green piece displayed a prism face and was polished into a 6.06-mm-thick wafer. The blue fragment was sliced parallel to the c-axis and polished into a 1.25-mm-thick wafer. Absorption spectra were collected in the 350-1100 nm range using a silicon diode-array microspectrometer with a calcite polarizer, and in the 1000-2000 nm region with a Nicolet Magna 860 FTIR spectrometer with a CaF_2 beam splitter, a deuterated triglycine sulfate detector, a tungsten-halogen lamp, and a LiI0_3 crystal polarizer