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set: minerals // series: // picture: Pyrite
PYRITECrystal faces represent the external expression of the internal structure of the mineral. This specimen of pyrite (iron disulphide, FeS2, approximately 20 cm across) shows one of its common crystal forms, where the faces are known as pentagonal dodecahedra (12 faces, each being 5-sided). Pyrite is a very common mineral but usually has little commercial value apart from that of making sulphuric acid
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