IIC irons
IIC irons are a small group of plessitic octahedrites rich in nickel and gallium relative to their structure.
IIC irons are a small magmatic group of iron meteorites with fewer than ten members. They contain roughly 9 to 12 per cent nickel and are notable for their fine structure: most are plessitic octahedrites, with very narrow kamacite spindles within plessite, a fine mixture of kamacite and taenite.
Their chemistry is distinctive, with relatively high gallium and germanium for their nickel content and other trace element signatures that show they formed in a separate core from other groups. Examples include Ballinoo from Western Australia.
Their fine structure records relatively rapid cooling for an iron meteorite, which suggests they came from a smaller body or one that lost much of its insulating mantle. Small groups like IIC are important because they show that many separate asteroid cores once existed, each with its own chemistry and cooling history. Etched IIC slices show delicate, shimmering patterns that reward close inspection.
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