| Summary: | P(論文) The droplet chondrules in Allan Hills-764 chondrite are grouped into three chondrule types on the base of their chemical compositions. They are sodic plagioclase (SP) chondrules, intermediate plagioclase (IP) chondrules and nepheline (N) chondrules. The SP-chondrules are the most common type and are composed mainly of the normative olivine, pyroxenes and sodic plagioclase components. The IP-chondrules consist of the normative olivine, pyroxenes and intermediate plagioclase components. The N-chondrules are rare and are composed of the normative olivine, nepheline and sodic plagioclase components. The actual minerals occurring in these droplet chondrules are not necessarily equal to the normative mineral compositions because of their metastable crystallization in rapid cooling conditions. Their crystallization sequences of minerals occurring in each chondrule type may be strongly controlled by their cooling rates. departmental bulletin paper
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