axiolitic structure

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axiolitic structure Elongate fibres of alkali feldspar intergrown with cristobalite which have nucleated and grown outwards from both sides of a linear fracture within rhyolitic glass. The fibres, which can be seen clearly only by using a petrological microscope, grow in the solid state during devitrification of the rhyolite glass, the linear fracture acting as the axis and nucleation point for crystals defining the structure.