Large, hopper-shaped pyrite octahedra occur in the Lower Jurassic shales on the northeast coast of Yorkshire, England. The crystals formed by direct precipitation, that is, without the formation of precursor monosulfides. Growth occurred by propagation of lineages (subcrystals) in {111} growth sectors, sometimes accompanied by growth in {100} sectors; and the crystals made room for themselves by pushing aside the enclosing sediment. Displacive crystallization succeeded passive precipitation of pyrite in the pore spaces of the sediment.

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