Greenalite
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Greenalite is a mineral in the kaolinite-serpentine group with the chemical composition 2-3Si2O54.
Greenalite (green) with galena and siderite, from Spain
Stilpnomelane
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Stilpnomelane is a phyllosilicate mineral. It has the chemical formula K81227·n.
Greenalite
…mineral in banded iron formations. Rocks which contain greenalite are usually bright green, pale green or pale brown. Greenalite occurs with quartz, stilpnomelane, siderite, chamosite, pyrite and minnesotaite. It is commonly oolitic. Greenalite, which is common in Archean rocks, formed rapidly in Archean seawater…
Stilpnomelane 217448