Chondrule (850 micrometers in diameter) from the unmetamorphosed Chainpur meteorite, containing excess ²⁶Mg from decay of ²⁶Al 4.6 billion years ago. Initial abundance of ²⁶Al is one-fifth of that in Ca-Al inclusions, the oldest solids formed in the solar system, implying that chondrules formed--and the solar nebula lasted--for more than 2 million years. The chondrule includes glass (dark magenta), brightly colored olivine and dendritic pyroxene, and blocky spinel (light magenta). See page 757. [Transmitted polarized light (plus gypsum plate) photo: G. J. MacPherson]

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