R1: Characterization and description of minerals (Joint Session with The Gemmological Society of Japan)

[R1-11] Origins and formation mechanisms of various organic minerals associated with hydrothermal silica veins

*Ryoji Tanaka^1,2, Yuki Inoue³, Takashi Ishibashi⁴, Akihito Hagiwara (1. Sagami Chemical Research Institute, 2. Tokai Univ., 3. Kyushu Univ., 4. Museum of Osaka Univ.)

Keywords:epithermal, polycyclic aromatic hydrocarbon, hokkaidoite, benzo[ghi]perylene, organic minerals

We found polycyclic aromatic hydrocarbon (PAH)-based organic minerals associated with epithermal silica veins at several sites in Japan, including two in Hokkaido. These consist of carpathianite (coronene crystals), benzo[ghi]perylene crystals, picene crystals, and the like. Although some solid-solution behavior is observed, most of them are molecular crystals of organic substances with high purity. This means that fractional crystallization occurs strongly in PAH-based organic minerals. Benzo[ghi]perylene was approved as a new mineral under the name of hokkaidoite.