R5: Extraterrestrial materials

[R5-13] Petrogenesis of silica polymorphs in eucrites

「発表賞エントリー」

*Rei Kanemaru¹, Akira Yamaguchi^1,2, Naoya Imae^1,2, Hirotsugu Nishido³ (1. SOKENDAI, 2. NIPR, 3. OUS)

Keywords:Eucrite, Silica polymorphs

Eucrites considered to originated from the surface crust of the asteroid 4 Vesta and suffered complex secondary processes. Silica minerals are a useful indicator for deciphering the P/T conditions of the secondary processes because silica mineral has many polymorphs. We identified the silica polymorphs in 16 eucrites. We found that the occurrence of the silica minerals in eucrites is strictly related to the cooling rate and post-crystallization history.