The igneous rocks that are characterized by two distinctly different crystal sizes are known as [tex]\boxed{{\text{Porphyritic textures}}}[/tex] .
Further explanation:
The crystal size or texture of igneous rocks is as follows:
1. Glassy texture: Glassy textures are the result of rapid cooling in volcanic rocks. There are very few mineral grains, but the rock mainly consists of volcanic glass or obsidian.
2. Aphanitic textures: Aphanitic textures are formed when volcanic rock cooled rapidly but allowed to form some crystal. These crystals are very small and cannot be able to see with naked eyes. The surface of these rocks is smooth but dull.
3. Fine-Grained textures: Fine-Grained textures are formed when the rock is crystallized but the individual crystals or grains are very small.
4. Porphyritic textures: These textures are the most common one in the volcanic rocks. These porphyritic textures consist of larger grains also called phenocrysts which are embedded in a fine-grained groundmass. Phenocrysts are crystallized when magma was still deep underground and then surrounded by the groundmass.
5. Pyroclastic textures: These textures result from the fusion of solid volcanic ejecta that has been welded into solid
6. Coarse-Grained textures: These textures are from slow cooling, and they are mostly larger crystals.
Therefore, the igneous rocks that are characterized by two distinctly different crystal sizes are known as porphyritic textures.
Learn more:
1. Determine the reason that causes water molecule a bent shape.: https://brainly.com/question/1979769
2.Determine how many moles of water produce: https://brainly.com/question/1405182
Answer details:
Grade: Senior school
Subject: Chemistry
Chapter: Solid state
Keywords: igneous rock, crystal sizes, textures, glassy texture, aphanitic textures, fine-grained textures, porphyritic textures, pyroclastic textures, and coarse-grained textures.
