Brightly Fluorescent Gem Hyalite Opal Specimen - San Luis Potosi, Mexico M20
Item History & Price
Reference Number: Avaluer:4634689 | Country/Region of Manufacture: Mexico |
Hyalite opal (Opal-AN) is a clear variety of opal, different from most other opal varieties. It is almost always fluorescent (bright green in shortwave UV) and has a strong vitreous luster. The opals from San Luis Potosi for...med underground as a result of precipitation of silica from a vapor phase. It is rare to see large examples of hyalite and it usually occurs as a ~1 mm coating on agates, chalcedony, or other opals. Hyalite typically contains less water than other opal varieties, usually around 3 to 8%. San Luis Potosi has the only large deposit of hyalite opals that often contain orange webbing, caused by iron inclusions. Orange webbing can be found from other locales, but is very rare.
Please note that you will need a shortwave UV blacklight to see the fluorescence! Regular blacklights and longwave lamps will cause little to no response. Around 90% of all minerals fluoresce in shortwave UV, while the others are longwave UV fluorescent.
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