Banded iron formation (BIF), hosted in the Shachang Formation of the Archean Miyun Group, a sequence of biotite-pyroxene granulite intercalated with amphibolitic granulite. There are four members in the formation: A, B, C and D. The middle part of Member C consists of amphibolic pyroxene plagioclase gneiss and pyroxene plagioclase gneiss and contains two iron-bearing layers with more than 50 orebodies, that are up to 780 m long and up to 93 m thick. The bodies are stratiform, lenticular and lensoid; swelling, pinching out, branching and mingling along the strike and dip directions are very common. The mineral textures are hypidiomorphic or xenomorphic granular and granoblastic; the structures are banded, laminated, gneissic and massive.
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http://wrgis.wr.usgs.gov/open-file/of03-220/DATABASE/lode_deposits.txt21 entries listed. 11 valid minerals.
