Color-change garnets

           TANZANIA CONTINUES TO POUR FORTH RICHES.  This was the beginning of a news item in the Jewelers' Circular-Keystone in July 1970.  The article goes on to say that in addition to tanzanite and chrome-tourmaline (which were then new materials for jewelers), Tanzania had produced a new type of garnet "gleaming red at night and green in daylight". 

           At the time, The Gemological Institute of America had just issued a preliminary report on the stone which our grandfather, Hyman Saul, Vice-President at Saks Fifth Avenue, had brought in to them.  Our father "Dr. John Saul of Nairobi" was credited with having found this then-unique "rolled pebble".  But as much as Dad would have liked to have made such a wonderful find, he refuses to take credit.  The stone had come to him from a Kenyan named Gideon who lived in a village in extreme SE Kenya, near the Tanzanian border.  In those days, it would have been illegal for him to have been prospecting or mining on the Tanzanian side.  But had he?  Probably, because Dad could never learn anything about where the unique stone had actually been found.

           In the decades since, a few other fine color-change garnets have been found in the region, mostly small and not all of them as spectacular as the original, but with some exceptions.  These have all been rounded pebbles and, as best we know, no more than one color-change garnet has been found at a time.  Usually they are found mixed in with the typical "normal" rhodolite garnets found in the gravel diggings in the Umba River Valley of extreme NE Tanzania.  But there is no known deposit of color change garnets as such, neither a primary deposit in the host rock, nor a concentration in the gravel of any of the tiny tributaries to the Umba so far prospected. MAP
           Does the primary deposit of color-change garnets still exist somewhere in the upper reaches of Tanzania's Umba River?  Back in the hills somewhere?  No one knows.  But stay tuned!

           (In the decades since the original find, several sources here and there in the world have produced color-change garnets.  Yet, aside from some tiny color-change garnets in Norway and a few nice stones from Madagascar, none of the newer finds seem to have produced stones as good as the as the original find.  (A deposit of garnets with a minor "color shift" has been found in the Taita Hills of Kenya and the stones are occasionally offered as color-change garnets, but they are in no way comparable to those described here and the stones show no green whatever.)