4.1: Classification of Igneous Rocks - Geosciences LibreTexts
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.
Igneous Rocks – Types, Properties, and Examples - Science Notes …
2024年1月31日 · Fine-grained or glassy textures are common in volcanic igneous rocks. Coarse-grained textures, where individual minerals are visible, are typical of plutonic igneous rocks. Sedimentary grains are often rounded, while metamorphic rocks have elongated minerals.
Basalt: Igneous Rock - Pictures, Definition, Uses & More - Geology.com
Basalt is a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. It most commonly forms as an extrusive rock, such as a lava flow, but can also form in small intrusive bodies, such as an igneous dike or a thin sill. It …
Basalt - Wikipedia
More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System.
Pictures and Descriptions of Igneous Rock Types - ThoughtCo
2019年6月2日 · Basalt is fine grained so the individual minerals are not visible, but they include pyroxene, plagioclase feldspar, and olivine. These minerals are visible in the coarse-grained, plutonic version of basalt called gabbro.
Igneous Rocks | Pictures of Intrusive and Extrusive Rock Types
Dacite is a fine-grained, extrusive igneous rock that is usually light in color. It has a composition that is intermediate between rhyolite and andesite. The specimen shown is about four inches (ten centimeters) across.
Rocks and Their Types - Sternberg Museum of Natureal History
These rocks have a fine-grained, or aphanitic, texture. When the lava cools very quickly, the rock has a glassy texture. Coarse-grained rocks tend to form beneath the surface of the Earth and fine-grained rocks tend to form at the surface.
4.3 Classification of Igneous Rocks – Principles of Earth Science
A rock with crystals that are too small to see with the unaided eye has an aphanitic or fine-grained texture. Table 4.1 summarizes the key differences between intrusive and extrusive igneous rocks. Slow: surrounding rocks insulate the magma chamber. Rapid: heat …
A Guide to Basalt: A Common, Fine-grained, Dark-Colored Volcanic Rock
2023年8月17日 · Basalt is a hard, fine-grained, dark-colored volcanic or extrusive rock. It has primarily calcium-rich plagioclase and augite. Also, it may have minor amounts of other minerals like quartz, olivine, foids, alkali feldspar, biotite, and amphibole. This rock is undoubtedly popular, only rivaled by granite.
Andesite: Igneous Rock - Pictures, Definition & More - Geology.com
Andesite is the name of a family of fine-grained, extrusive igneous rocks that are usually light to dark gray in color. They have a mineral composition that is intermediate between granite and basalt. Andesite is a rock typically found in volcanoes above convergent plate boundaries between continental and oceanic plates.