Crystallization of dmisteinbergite (hexagonal CaAl2Si2O8) from type B CAI analog meltOPEN ACCESS 

· by · in ,

Yasuaki Tsuruoka, Hideto Yoshida, Yuki Inoue, Daiki Yamamoto, Hiroyuki Kagi, Akira Miyake, Shogo Tachibana

MAPS, Version of Record online: 27 July 2026

LINK (OPEN ACCESS)
PDF (OPEN ACCESS)

“Dmisteinbergite is a metastable polymorph of CaAl2Si2O8, which has been found in calcium−aluminum-rich inclusions (CAIs) in chondrites, although anorthite is the predominant CaAl2Si2O8 phase in natural type B CAIs. The occurrence/absence of igneous dmisteinbergite would put tighter constraints on the thermal history of CAIs. However, little attention has been paid for crystallization of dmisteinbergite in CAI melts even though its kinetically controlled crystallization (i.e., crystallization from a supercooled melt) has been proposed. In this study, we conducted dynamic crystallization experiments on CAI analogs in the presence of low-pressure hydrogen gas (1–10 Pa) to simulate the formation of igneous CAIs and to understand crystallization behavior of CaAl2Si2O8 phases. Dmisteinbergite was found in samples cooled at rates of 1–20 °C h−1, while anorthite was found in samples cooled at 5 °C h−1, suggesting that the slow cooling (likely slower than on the order of 1 °C h−1) might promote the formation of anorthite. Because the slow cooling rates during the final stage of crystallization of CAIs likely reflect conditions approaching the background temperature of CAI-forming regions, CaAl2Si2O8 phases in type B CAIs could constrain the thermal history and formation environment of those regions.”

Related posts (automatically generated):

  1. Hydrothermal origin of hexagonal CaAl2Si2O8 (dmisteinbergite) in a compact type A CAI from the Northwest Africa 2086 CV3 chondrite
  2. The Formation of Type B CAIs: Evolution from Type A CAIs
  3. Type B–type C CAI in a CR chondrite: Evidence for multiple melting events, gas–melt interaction, and oxygen-isotope exchange
  4. Mineralogical alteration of a type A CAI from Allende CV3 chondrite: Formation of secondary dmisteinbergite and its phase transition to anorthiteOPEN ACCESS 
  5. Textural and compositional evidence for in situ crystallization of palisade bodies in coarse‐grained Ca‐Al‐rich inclusions
  6. Nebular history of an ultrarefractory phase bearing CAI from a reduced type CV chondriteOPEN ACCESS 
  7. 26Al-26Mg chronology and oxygen isotope distributions of multiple melting for a Type C CAI from Allende
  8. Oxygen and Al-Mg isotopic constraints on cooling rate and age of partial melting of an Allende Type B CAI, Golfball
  9. Solar System’s earliest solids as tracers of the accretion region of Ryugu and Ivuna-type carbonaceous chondritesOPEN ACCESS 
  10. Mineralogical and isotopic constraints on early, high-temperature events and reservoirs recorded in the interior of a Type B Ca-Al-rich inclusion from the reduced CV3 chondrite VigaranoOPEN ACCESS 
Tags: , , ,