Some other examples are Andesite, Basalt, Rhyolite, and Scoria.
Some igneous extrusive rocks include obsidian, basalt, andesite, rhyolite, scoria, pumice, basaltic glass. If you want more, go to page 6 on the Earth Science Reference Tables at the related link.
because you can tell them more easily
When lava reaches the surface of the Earth through volcanoes or through great fissures the rocks that are formed from the lava cooling and hardening are called extrusive igneous rocks. Some of the more common types of extrusive igneous rocks are lava rocks, cinders, pumice, obsidian , and volcanic ash and dust
They are made slowly. This is why they have a coarse-grained or rough texture. On the other hand there are extrusive igneous rocks, which are formed quuickly. These have a fine-grained or smoother texture. Intrusive rocks have more time to cool, so the mineral crystals can grow bigger, but extrusive rocks have lss time for their mineral crystals to grow.Igneous rocks form when magma cools and hardens.
All molten rock is capable of cooling quickly into fine-grained rocks, but here are some common fine-grained igneous rocks: Basalt Obsidian Andesite Rhyolite Tuff (a rock made from volcanic ash)
Intrusive igneous rocks is formed from magma that cools, solidifies, crystallizes, and hardens slowly within the earth's crust, and this makes its crystals large. In the case of the extrusive igneous rocks, they develop from the rapid cooling, solidification, crystallization and hardening of lava on the earth's surface and this makes them more smooth and having minerals with crystals of smaller size.
Intrusive, or plutonic, based upon the size of the crystals. Intrusive igneous rocks tend to have larger and more developed crystals than volcanic igneous rocks because of minimal exposure to air, causing the magma to cool more slowly.
There are many varieties of igneous rock. Igneous means it formed as a result of volcanic activity (the word igneous comes from the same root word as ignite) which produces extreme heat. Two main types of igneous rocks are intrusive (cooled gradually underground) and extrusive (cooled more rapidly at or near the surface.) Common examples of igneous rocks include granite, pumice, obsidian, basalt, diorite, andesite.
Large Crystals = Intrusive Small Crystals = Extrusive The name relates to where the minerals were cooled (at at what rate). In the case of intrusive igneous, the rocks were formed above Earth's surface and were thus cooled quickly and the minerals had little time to become defined. Extrusive rocks, therefore, were formed within the Earth's mantle and had a much longer time before being gathered to cool (as they slowly rose to the top).
Where magma erupts on the surface of the earth, temperatures are lower and cooling of the magma takes place much more rapidly. This is the extrusive or volcanic environment and results in extrusive or volcanic igneous rocks.
basalt
The description oof it is big grains and there are visual and you can touch them always remember that it is intrusive igneous rock not extrusive rock igneous rock. and the color of it is GRAY!!!! Thankz for asking the questions ask more