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Spring 1936, Blue-green Spinels (with R.I. of 1.73 and S.G. of 3.65), by Anderson, p. 8, 1p.
Summer 1938, Toughness of Spinel, p. 174, 1p.
Fall 1943, Identifying Synthetic Spinel, p. 103, 1p.
Summer 1944, Black Star Spinel, p.
Green spinels are rare, and colorless stones are virtually nonexistent.
 See also: Jewel, Crystals, Red spinel, Synthetic, Jewelry
  
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