Ruby-in-Zoisite SlabLongido Mine, Arusha, Tanzania In 1949, Tom Belvins and another English prospector, both residents of Kenya, made a discovery of a ruby deposit not far from Mount Kilimanjaro. In a shallow basin they found a breathtaking display of flat, sharp-faced, hexagonal, deep red ruby crystals in a green zoisite outcrop, the matrix in which the ruby crystals were formed. The crystals rarely exceeded two inches in diameter by a quarter of an inch in thickness. Another 150 feet along the strike of the outcrop, a noticeable change occurred to the rubies, still immersed in the green matrix. They became much larger but coarser in outline, changing from the thin, flat crystals with transparent areas into huge hexagonal columns of a lighter red opaque material. The most distant outcrop from the original discovery was approximately four hundred feet, at which point the exposed rubies were sparsely scattered, poorly formed and opaque, but extremely large. From the standpoint of sheer quantity, this locality is the largest producer of ruby ever known. In later years, when the claim was in the hands of new owners, shafts were driven down into the green zoisite and for many years rubies were mined, totaling hundreds of thousands of carats, much of this production being sent to India to be cut into small faceted gems. The present slab is a fine cross-section of a boulder of bright green zoisite with a hexagonal crystal of ruby to the center. It possesses the right degree of thickness to show transmitted light to best display the ruby. Measuring 4 x 2 3/4 x 1/4 in (10.5 x 7 x 0.2 cm); Weight: 42 grams. Apanied by a custom-fitted stand.