Honduran and Turkish Opal
Harald Mühlinghaus (Opal Imperium, Enkirch, Germany) has been exhibiting at the Pueblo Gem & Mineral Show for more than 20 years. The company sources, fabricates, and sells a number of colored gemstones, but their main focus is opal from Australia, Mexico, Honduras, and other locales. At the booth were some unusual examples that have rarely been documented, such as the banded opal in the left-hand image, obtained about 30 years ago from an unrecorded Honduran location. This material occurs as solid vertical veins in matrix with approximately 1 cm stratifications of play-of-color, which indicate the cyclical concentration and the formation of the silica spheres that form opal. The phenomenon is most distinct in fairly sizable pieces of rough, with 1–3 mm opal layers on matrix measuring 5–15 cm across, which makes these specimens more suitable for display than for jewelry. Some of the smaller examples displayed only nonphenomenal layers, while others had play-of-color fading to potch at each cycle.
Also on display were dendritic opal cabochons (right) from rough obtained from Simav, Turkey, about four years ago. This material, which Mühlinghaus called “Turkish dendritic opal,” has been cut so that each piece shows clearly delineated opaque white and semitransparent areas, embedded with fine branched black inclusions reminiscent of traditional Japanese tategaki characters.
