BY BOB JONES
Specimen of amber. HANNES GROBE, WIKIMEDIA COMMONS
Of all the elements on the Periodic Table, a small cluster of transition metal elements play a major role in determining the value of many popular and valuable gems. For example, zoisite is usually an opaque pink thanks to manganese and green due to a trace of chromium. But zoisite variety tanzanite is an astoundingly wonderful and colorful gem.The very valuable and vibrant blue to violet tanzanite is from Tanzania. Few realize the great majority of the tanzanite found has a brownish tint because the trace vanadium in it has a valence of three electrons. To learn more about tanzanite, please turn to page 10 of this issue to enjoy my feature article. The importance of trace impurities of transition metal elements in otherwise less attractive gems can not be overstated. Except for diamonds, which have high value even when colorless, it is the colorful gems that command higher prices in the market.