Applicability of condensation calculations to the early solar system

Applicability of condensation calculations to the early solar system 

Consider first the CAIs. In general, their bulk compositions are consistent with those calculated for the first 5% of condensable matter (Davis and Richter, 2004). Moreover, many of the minerals that comprise CAIs (hibonite, perovskite, spinel, melilite, diopside, anor-thite) are predicted to have been the earliest condensed phases. However, not all CAIs are 

Backscattered electron image of a Type CAI in the Allende CV3 chondrite. This object crystallized from a melt and has an outer mantle of melilite (Mel) surrounding an inner zone of pyroxene (Px) and anorthite (An). Tiny grains of spinel (Sp) are abundant in the inner portion of the inclusion. Image courtesy of A. Krot. 

On the other hand, fine-grained CAIs consist of aggregates of nodules with a concentric structure consisting of spinel cores surrounded by melilite, anorthite, and diopside, or melilite cores surrounded by anorthite and diopside (Fig. 7.5). The sequence of minerals in the nodules is consistent with a condensation sequence. However, the textures of the overall objects are complicated and often indicate extended and multistage histories. For 

Backscattered electron image of a portion of a fine-grained Type A CAI in the Efremovka CV3 chondrite. This inclusion consists of nodules of spinel (sp) surrounded by anorthite (an) and thin rims of pyroxene (px). This CAI may be an aggregate of condensates. 

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