Host: The Gemmological Society of Japan
Pages 6
In this study, we have shown that the UV fluorescence (FL) of opal from Shikaribetsu area, Shikaoi-cho, Hokkaido, is due to the presence of polycyclic aromatic hydrocarbons (PAHs). The opal, which exhibits a variety of color FL upon irradiation with long-wave UV, was crushed, chloroform-extracted, and analyzed for soluble components by HPLC. And luminescent component was found to be PAHs with a molecular weight of 150 to 400. Orange FL is due to finely dispersed bitumen in opal, and yellow to yellow-green FL is due to crystalline PAH inclusions such as coronene (Cor) and benzo[ghi]perylene (BPer) crystals. Crystalline Cor is carpathite, and crystalline BPer is a new mineral, approved by International mineralogical association in 2023 as hokkaidoite.
