cryptocrystalline texture

geology

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June 25, 2026

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In geology, cryptocrystalline texture refers to a very fine-grained crystalline material where the individual crystals are too small to be resolved even under a microscope. This texture is a characteristic of aphanitic rocks, which form from magma that cools relatively quickly, typically in volcanic environments.1

Igneous rocks are classified by their texture, which includes crystallinity and granularity. Crystallinity describes whether a rock is entirely crystalline, contains a mix of crystals and glass, or is entirely glassy. Granularity refers to the size of the mineral grains. Aphanitic rocks, including those with cryptocrystalline texture, indicate rapid cooling.12

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igneous rock
Crystallinity
…described as either microcrystalline or cryptocrystalline, according to whether or not their individual constituents can be resolved under the microscope. The subaphanitic, or hyaline, rocks are referred to as glassy, or vitric, in terms of granularity.
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…described as either microcrystalline or cryptocrystalline, according to whether or not their individual constituents can be resolved under the microscope. The subaphanitic, or hyaline, rocks are referred to as glassy, or vitric, in terms of granularity.
Read More