Maine Gemstone or Gem

Tourmaline

Complex Aluminium Borosilicate

Adopted in 1971.

Tourmaline, Complex Aluminium Borosilicate, was adopted in 1971.It occurs as lustrous, elongate crystals which commonly have a rounded triangular cross section and narrow grooves running parallel to their long direction.

The crystals range in size from microscopic to over a foot long. The best examples in Maine are found in a very coarse-grained type of granite called "pegmatite". The slow cooling and solidification of the pegmatite veins allowed the mineral grains to grow to much larger sizes than in ordinary granite. The black tourmaline crystals and many of the brightly colored ones are usually encased in the surrounding rock. However, conditions in some places favored the development of open cavities in which elbaite crystals grew with greater perfection and clarity. These pegmatite "pockets" are the source of Maine's finest gem tourmalines.

Several spectacular tourmaline pockets were discovered in the Dunton Mine in Newry, Maine, in 1972. Many fabulous red and green crystals were found, including the ten-inch "Jolly Green Giant," which is now in the National Museum of Natural History in Washington, D.C.

Tourmaline comes in many colors such as blue, yellow, pink, red, black, green and clear. Tourmaline comes in many colors - but primarily in pink and green. It is beautiful in rings, necklaces, and pendants.  

Colors:

• Indicolite (blue or blue-green) -- moderately scarce and expensive in fine qualitities.
• Rubellite (red) -- moderately scarce and expensive in fine qualitities. Often badly included.
• Bicolor or tricolor tourmaline -- shows multiple color zones throughout the crystal. Highly prized when the colors are well divided and vivid. Often badly included and subject to fracture along the color transition line.
• Watermelon tourmaline -- has a red central core surrounded by green, resembling the cross section of a watermelon. Often cut in thin slices to show the colors to best advantage.
• Schorl -- black tourmaline.
• Dravite -- brown tourmaline.
• Chrome tourmaline -- vivid green. Derives its color from chromium. Appears red when viewed through a Chelsea filter (emerald filter). Fairly scarce and expensive.
• Achroite -- colorless tourmaline. Fairly rare.