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
false
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.
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
Large crystals are diagnostic of an intrusive igneous rock, as large crystals form as the source magma cools slowly.
True. Intrusive igneous rock, also known as plutonic rock, forms larger crystals because it cools slowly underground. Extrusive igneous rocks cool rapidly on the Earth's surface, forming smaller crystals.
Intrusive rocks form beneath the earth's surface, so they cool very slowly, which produces larger crystals.
Because as an intrusive rock cools underground, it will normally cool more slowly than an extrusive (surface) rock. The slow cooling allows more time for the crystals to grow.
Porphyrite of any composition, granite, gabbro, diorite. Most intrusive igneous rocks have crystals large enough to see with the naked eye. Another term used to define an igneous rock with large crystals is coarse-grained.
A porphyritic igneous rock demonstrates some extrusive characteristics and some intrusive characteristics. The appearance of phenocrysts (larger crystals) in a fine matrix (small crystals) indicates that the magma had time to cool slowly enough underground to form larger crystals before being erupted at or near the surface.
Intrusive Rocks are found underneath Earths crust, while Extrusive rocks are found above Earths crust.
instrusive Rock