Igneous Rock With Name On Picture Obsidan Pumice And Granite

We know igneous rocks have two basic types.

Igneous rock with name on picture obsidan pumice and granite.

Granite is an intrusive igneous rock. Scoria like pumice is a lightweight extrusive rock. Intrusive rocks form from molten material magma that flows and solidifies underground where magma cools slowly. It is the most common plutonic rock of the earth s crust forming by the cooling of magma silicate melt at depth.

Extrusive igneous rocks erupt onto the surface where they cool quickly to form small crystals. All pictures of igneous rocks are courtesy of the usgs united states geological survey with the exception of granite. Today we are going to know obsidian rock which falls in the main class igneous rocks. Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock.

Pictures and brief descriptions of some common igneous rock types are shown on this page. Learn more about the properties and uses of granite in this article. Clicking on the name of the rock will bring up a larger picture and a description of the rock type in a new window. Igneous rocks that solidified within the crust are plutonic or intrusive rocks.

When molten lava magma is cooling slowly below the surface of the earth and forms large crystals in the rocks they known as intrusive igneous rocks. Obsidian is produced when felsic lava extruded from a volcano cools rapidly with minimal crystal growth it is commonly found within the margins of rhyolitic lava flows known as obsidian flows where the chemical composition high silica content causes a high viscosity which upon rapid cooling results in. The table below shows examples of common metamorphic rocks. Some cool so quickly that they form an amorphous glass.

Obsidian is extremely rich in silica about 65 to 80 percent is low in water and has a chemical composition similar to rhyolite. Molten rock material below the surface is called magma. Eventually the overlying rocks are removed exposing the granite. Obsidian is an igneous rock that forms when molten rock material cools so rapidly that atoms are unable to arrange themselves into a crystalline structure.

Magma that has reached the surface is lava. Granite coarse or medium grained intrusive igneous rock that is rich in quartz and feldspar. Granite is the most widespread of igneous rocks underlying much of the continental crust. Another name for scoria is volcanic cinders and the landscaping product commonly called lava rock is scoria as is the cinder mix widely used on running tracks.

Igneous rocks from left to right. This type of igneous rock has large distinct gas bubbles and a darker color. These rocks include andesite basalt dacite obsidian pumice rhyolite scoria and tuff. Obsidian has a glassy lustre and is slightly harder than window glass.

It is an amorphous material known as a mineraloid the result is a volcanic glass with a smooth uniform texture that breaks with a conchoidal fracture see photo.