What are the characteristics of intrusive and extrusive igneous rocks?
The two main categories of igneous rocks are extrusive and intrusive. Extrusive rocks are formed on the surface of the Earth from lava, which is magma that has emerged from underground. Intrusive rocks are formed from magma that cools and solidifies within the crust of the planet.
Which of the following are characteristics of extrusive rocks?
Extrusive rocks are usually distinguished from intrusive rocks on the basis of their texture and mineral composition. Both lava flows and pyroclastic debris (fragmented volcanic material) are extrusive; they are commonly glassy (obsidian) or finely crystalline (basalts and felsites).
What are the features of extrusive igneous rocks and how do these rocks form?
Igneous rocks are called extrusive when they cool and solidify above the surface. These rocks usually form from a volcano, so they are also called volcanic rocks (Figure below). Extrusive igneous rocks form after lava cools above the surface. Extrusive igneous rocks cool much more rapidly than intrusive rocks.
What are the 3 characteristics of intrusive igneous rocks?
Characteristics of Intrusive Rocks
- Formation. Intrusive rocks are formed from magma deep in the earth.
- Texture. Rock textures refer to crystal characteristics visible with the unaided eye.
- Color. Igneous rocks are categorized by light, medium and dark colors.
- Intrusive Rock Formations.
What is the texture of extrusive igneous rocks?
Extrusive igneous rocks have a fine-grained or aphanitic texture, in which the grains are too small to see with the unaided eye. The fine-grained texture indicates the quickly cooling lava did not have time to grow large crystals.
What texture do extrusive igneous rocks have?
fine-grained
Extrusive igneous rocks have a fine-grained or aphanitic texture, in which the grains are too small to see with the unaided eye. The fine-grained texture indicates the quickly cooling lava did not have time to grow large crystals.
What are some clues that a rock is an extrusive igneous rock?
Igneous rocks are classified into two categories: intrusive and extrusive rocks. Extrusive rocks form from lava that crystallizes on the earth’s surface. Two good indicators to help you decide whether you are looking at an extrusive rock are small crystal size and the presence of vesicles.
What are the three textures for extrusive rocks?
Igneous Rock Textures
- COARSE GRAINED TEXTURE (PHANERITIC), mineral grains easily visible (grains several mm in size or larger)
- B) FINE GRAINED TEXTURE (APHANITIC), mineral grains smaller than 1mm (need hand lens or microscope to see minerals)
- C) PORPHYRITIC TEXTURE (MIXED FINE AND COARSE)
Which characteristic is best for identifying whether a rock is intrusive or extrusive?
Intrusive igneous rocks cool from magma slowly in the crust. They have large crystals. Extrusive igneous rocks cool from lava rapidly at the surface. They have small crystals.
What are the extrusive igneous rock structures?
Extrusive Igneous Rock This results in rocks with a very fine-grained or even glassy texture. Hot gasses are often trapped in the quenched lava, forming bubbles (vesicles). Types of extrusive igneous rocks include: pumice, obsidian, andesite, rhyolite, and basalt.
What textures are possible in extrusive rocks?
Extrusive igneous rocks will have aphanitic, vesicular, glassy, or pyroclastic textures.
What is the texture of extrusive igneous rock?
Which describes a feature of extrusive igneous rocks after formation?
Which describes a feature of extrusive igneous rocks after formation? An igneous rock has large red, black, and green crystals.
Which characteristics is best for identifying whether a rock is intrusive or extrusive?
Which characteristic is best for identifying whether a rock is intrusive or extrusive color? The rate at which magma cools determines whether an igneous rock is intrusive or extrusive. The cooling rate is reflected in the rock’s texture.
Which describes a feature of extrusive?
Do extrusive igneous rocks have crystals?
Extrusive igneous rocks form after lava cools above the surface. Extrusive igneous rocks cool much more rapidly than intrusive rocks. There is little time for crystals to form, so extrusive igneous rocks have tiny crystals (Figure below). Cooled lava forms basalt with no visible crystals.