This is a Cahnite, an extremely rare mineral even by Franklin standards, found just once in gem crystal quality in a small pocket in 1921 by a collector named Stanton. This one is even more rare...it is complexly twinned! However, the pics are tough and the piece is clear and difficult to shoot. This piece went to Harvard, and then it was exchanged to Dr. Mark Feinglos at some point. It has resided since in his collection for many years. These come to market only in recycled collections of ultimate rarities. It is pretty small by some standards; but relatively speaking though it is a giant of a piece for what it is. It is of a size that the twinning is readily visible to the eye. Again, 1 x 0.8 x 0.5 cm.
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