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    STUDIA GEOLOGIA - Issue no. 3 / 2003  
         
  Article:   MINERAL INCLUSIONS IN RUBY FROM ANDILAMENA, MADAGASCAR.

Authors:  PANJAWAN THANASUTHIPITAK, THEERAPONGS THANASUTHIPITAK, KOBKARN PHETPHU. 		 
       
         
  Abstract:  Gem – quality rubies from the Andilamena area in eastern Madagascar have recently entered the gemstone market in commercial quantities. These rubies typically occur as short-prismatic or plate-like crystals with saturated purplish red to red colour. Triangular growth pattern on their basal surfaces is common. Mineral inclusions in 31 out of 245 samples were studied using Raman spectroscopy and scanning electron microscopy. The most common mineral inclusions are rutile, apatite and zircon. Monazite is sometimes identified. Staurolite, spinel, mica(?) and pyrite(?) are occasionally found. Rutile occurs as both primary and secondary crystals. Primary rutile forms isometrical to elongated crystal of orange to reddish brown or gray to black colour with metallic luster standing out in high relief. Secondary short rutile needles form dense clouds often concentrating in the center of some ruby crystals. These represent exsolved rutile needles and are oriented in 3 directions, parallel to second-order hexagonal prism. After heat treatment, the secondary rutile needles were completely dissolved. ...  
         
     
         
         
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