Why Does Granite Have Bigger Crystals Than Basalt

Like gabbro granite and diorite basalt is an igneous rock and is also the most abundant bedrock on earth including under the surface and within ocean basins.

Why does granite have bigger crystals than basalt.

Obsidian and granite are igneous rocks so called because they were formed from the molten magma of volcanoes. This slow cooling gives time for crystals to grow making it more coarsely grained than an extrusive rock. Why does granite have a lower melting point than basalt. Yes because granite is a slow cooling rock therefore the crystals have a lot of time to form while basalt is a fast cooling rock therefore thecrystals don t have much time to form and develop.

Beyond that their similarities end. Intrusive igneous rocks have cooled slowly from magma extrusive rocks have. Crystals have more time to grow to larger size. Granite is an intrusive rock that is formed when magma cools inside the crust.

Basalt on the other hand has a smooth texture from rapid cooling usually by water. Granite contains more water and minerals that melt at lower temperatures rocks that are rich in which 2 elements melt at higher temperatures than rocks that contain higher levels of silicon. If magma cools quickly for example when basalt lava erupts from a volcano then many crystals form very quickly and the resulting rock is fine grained with crystals usually less than 1mm in size. This coarse grain makes granite a favorite of rock climbers.

Intrusive igneous rocks have cooled slowly from magma extrusive rocks have. Basalt rocks have fine grained crystals while gabbro is made up of much larger coarse grained pieces. The crystals in granite being intrusive in nature will be larger than those in basalt an extrusive igneous rock. It depends on the type of igneous rock.

Obsidian is not a genuine mineral or rock it is a natural glass that contains microscopic mineral crystals. What s the most obvious difference between basalt and gabbro.