even-grained rock

Also known as: equigranular rock

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June 26, 2026

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An even-grained rock, also known as equigranular, is characterized by crystals of nearly the same size. This textural feature is a key characteristic used to describe igneous rocks, providing insights into the conditions under which they formed. The size of mineral grains is a primary descriptor of igneous rock texture, with finer grains typically being less than 0.3 millimeters in diameter. While the term "even-grained" specifically refers to the uniformity of crystal size, other textural descriptions like "fine-grained" or "dense" relate to the overall smallness of the grains.12

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igneous rock
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Even-grained, or equigranular, rocks are characterized by essential minerals that all exhibit the same order of grain size, but this implied equality need not be taken too literally. For such rocks the combination terms panidiomorphic-granular, hypidiomorphic-granular, and allotriomorphic-granular are applied according to the occurrence of…
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Even-grained, or equigranular, rocks are characterized by essential minerals that all exhibit the same order of grain size, but this implied equality need not be taken too literally. For such rocks the combination terms panidiomorphic-granular, hypidiomorphic-granular, and allotriomorphic-granular are applied according to the occurrence of…
Read More