What is a coarse grained igneous rock?
Table of Contents
What is a coarse grained igneous rock?
Coarse-grained textures generally indicate magmas that slowly cooled deep underground. Slow cooling gives crystals enough time to grow to easily seen sizes (i.e., larger than 1 mm). The first-formed crystals tend to have regular shapes because they grow freely into the surrounding liquid.
What type of igneous rocks are coarse and grained?
Igneous rocks may be simply classified according to their chemical/mineral composition as felsic, intermediate, mafic, and ultramafic, and by texture or grain size: intrusive rocks are course grained (all crystals are visible to the naked eye) while extrusive rocks may be fine-grained (microscopic crystals) or glass ( …
What type of rock is coarse grained?
crystalline igneous rock
A coarse-grained, crystalline igneous rock is an igneous rock that contains coarse-grained silicatic minerals. Coarse-grained magmatites which are completely crystallized belong to the group of the intrusive magmatites (plutonites), their chemical composition is variable, depending on the magmatic source rock type.
Are igneous rocks coarse or 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. These tiny crystals can be viewed under a petrographic microscope [1].
Is Obsidian coarse grained?
Coarse grain varieties (with mineral grains large enough to see without a magnifying glass) are called phaneritic. Granite and gabbro are examples of phaneritic igneous rocks. The most common glassy rock is obsidian.
Is biotite mafic or felsic?
Image Descriptions
| Igneous Rocks | Felsic | Mafic |
|---|---|---|
| Biotite and/or Amphibole | 0 to 20% | 0 to 30% |
| Pyroxene | 0% | 20 to 75% |
| Olivine | 0% | 0 to 25 % |
| Intrusive | Granite | Gabbro |
Is pumice coarse or fine grained?
pumice is a very fine grained (often the grains are not visible by naked eye), light coloured, light weight, highly vesicular acidic volcanic glass. Pumice is a special kind of volcanic glass formed by the solidification of lavafoam permeated with gas bubbles.