What are the 2 basic classifications of 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.

What are the 6 different igneous rocks and how are they classified?

Igneous Rock Textures There are six main types of textures; phaneritic, aphanitic, porphyritic, glassy, pyroclastic and pegmatitic. Aphanitic (a = not, phaner = visible) rocks in contrast to phaneritic rocks, typically form from lava which crystallize rapidly on or near Earth’ surface.

What are the 5 types of igneous rocks?

These rocks include: andesite, basalt, dacite, obsidian, pumice, rhyolite, scoria, and tuff. Pictures and brief descriptions of some common igneous rock types are shown on this page.

What 3 characteristics are used to classify igneous rocks?

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 ( …

Which is the best classification of igneous rocks?

Figure 3.4.1 A simplified classification diagram for igneous rocks based on their mineral compositions. [Image Description]

How are igneous rocks different from intrusive rocks?

Igneous rocks are those that form via the process of melting and cooling. If they erupt from volcanoes onto the surface as lava, they are called extrusive rocks. By contrast, Intrusive rocks are formed from magma that cools underground.

How are igneous rocks formed on the surface of the Earth?

Igneous rocks are formed when magma cools, either on Earth’s surface or beneath it, though some may form by fragmentation of solidifying magma. Typical occurrences of igneous rock bodies on the surface include lava flows, lava domes, necks and spines, and pyroclastic deposits.

How are pyroxene and feldspar used to describe igneous rocks?

A given rock is represented by a vertical line in the diagram. In the mafic field, the arrows represent a rock containing 48% pyroxene and 52% plagioclase feldspar. The name an igneous rock gets depends not only on composition, but on whether it is intrusive or extrusive.