Intrusive rock normally has visible crystals. Extrusive igneous rock has small crystals. A black extrusive igneous rock with small crystals could be basalt.
by the size of the crystals, big crystals intrusive, small crystals extrusive
If a rock has large crystals, it is an intrusive rock. Intrusive rocks form underneath the Earth's surface. Magma cools slowly so it has time to form large crystals. An example is granite, where you can see the crystals with your naked eye. Rocks that have small crystals are extrusive rocks. Extrusive rocks are ones that form from lava (blasted out of a volcano) so they cool very quickly, not allowing large crystals to form. An example is obsidian, where you cannot visibly see the small crystals; it just looks like one black, glassy rock.
false
Intrusive
It depends on the type of igneous rock. Intrusive igneous rocks such as granite have large crystals, extrusive igneous rocks may have small crystals as in basalt or no crystals as in pumice.
As a general rule extrusive igneous rock crystals are very small, often microscopic, as the rock cools very rapidly. Conversely intrusive magma often cools so slowly that sizeable crystals can develop.
False
Large crystals are diagnostic of an intrusive igneous rock, as large crystals form as the source magma cools slowly.
Because intrusive rocks cool more slowly which makes the rocks larger.
The texture depends on the size and shape of the crystals you see in it. The larger the crystals, the slower the rate of cooling. This suggests that it is an intrusive rock. Smaller crystals suggest more rapid cooling indicating that it is an extrusive rock. INTRUSIVE- cooled inside the earth and had more time to create crystals EXTRUSIVE- cooled on the surface of the earth and created small crystals
Yes. Gabbro is an intrusive igneous rock with visible mineral crystals.
Intrusive rocks form beneath the earth's surface, so they cool very slowly, which produces larger crystals.