An apparently unique dioptase specimen from a very uncommon Mexican locality - km 1865 on the Guadalajara-Nogales Highway. Gemmy, emerald-green dioptase crystals richly cover both sides of the showy and different-looking rhyolitic gossan matrix. One side has many, small vugs filled with dioptase crystals. The other side is a large, quartz-lined vug richly sprinkled with isolated dioptase microcrystals. Ex. Fred Pough and George Elling Collections.