quartzite

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quartzite A metamorphic rock composed mainly of quartz and usually formed by the metamorphism of quartz sandstones. If deformation has accompanied metamorphism the individual quartz crystals are elongate and take on a preferred orientation, defining a planar or linear fabric within the rock. Unmetamorphosed sedimentary quartzites (sandstones with a quartz cement) are known as ‘orthoquartzites’ to distinguish them from metamorphic quartzites (metaquartzites).

quartzite

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quartzite Metamorphic rock usually produced from sandstone, in which the quartz grains have recrystallized. Quartzite is a hard and massive rock. It is usually white, light grey, yellow or buff, but it can be coloured green, blue, purple, or black by various minerals.