Igneous Metamorphic Sedimentary Rock Gallery

The Rock Gallery contains pictures and descriptions of common igneous,  metamorphic, and sedimentary rocks. The igneous rocks, like the granite that makes up half Dome, in Yosemite National Park, pictured above, are listed at the top of the page followed by metamorphic rocks. The sedimentary rocks are at the bottom of the page.

The following is an example of igneous rocks. It is not an all inclusive list but a brief pictorial list of some common igneous rocks.

Examples of Common Igneous Rocks
Andesite Andesite is a gray to black volcanic rock. It is generally erupted from stratovolcanoes as thick lava flows. It can also generate strong explosive eruptions to form pyroclastic flows.
Basalt-lava Basalt - Basalt is a hard, black volcanic rock. Less than ½ of the weight of basalt is silica (SiO2). Because of basalt's low silica content, it has a low viscosity (resistance to flow). This enables basaltic lava to flow quickly and allows volcanic gases to escape without explosive events.
Dacite Dacite lava is most often light gray, but can be dark gray to black. It is one of the most common rock types associated with enormous Plinian-style eruptions.
Pumice Pumice is light and porous. It forms during explosive eruptions. Pumice is full of holes caused by expanding volcanic gases. It is composed of volcanic glass and minerals, and can form in all types of magma: basalt, andesite, dacite, and rhyolite.
Obsidian Obsidian is usually black in color though it can also be red or have a greenish tint. It is a dense volcanic glass, usually composed of rhyolite, rich in iron and magnesium. Obsidian is formed when the lava cools so quickly that crystals do not have time to grow. Obsidian fractures with very sharp edges. It was used by Stone Age cultures for making knives, arrowheads, and other tools where sharp edges are important.
Rhyolite Rhyolite is a light-colored volcanic rock. It has a high silica content which makes it very viscous. This prevents gases from escaping causing rhyolite eruptions to be explosive.
granite Granite is a common intrusive plutonic igneous rock. Because it cools slowly crystals have time to form. The name granite comes from the Latin word granum which means “a grain” for the coarse grain crystalline structure of the rock.
All pictures of igneous rocks are courtesy of the USGS - United States Geological Survey with the exception of granite. Discriptions are adapted from the USGS. The table below shows examples of common metamorphic rocks. Clicking on the name of the rock will bring up a larger picture and a description of the rock type in a new window.
Examples of Common Metamorphic Rocks
quartzite Quartzite is a coarse-grained metamorphic rock derived from sandstone.
marble Marble is a metamorphic rock that comes from metamorphosed limestone or dolomite.
slate Slate is a fined grained metamorphic rock.
phyllite Phyllite is a fined grained metamorphic rock.
schist Schist is a course grained metamorphic rock.
gneiss Gneiss is a medium to course grained metamorphic rock.
The table below shows examples of common clastic sedimentary rocks. They are listed by grain size in decending order. Grain size is one factor in classifying sedimentary rocks. Clicking on the name of the rock will bring up a larger picture and a description of the rock type in a new window.
Examples of Clastic Sedimentary Rocks
Conglomerate Conglomerate is made up of rounded pebbles cemented together.
Breccia Breccia is made up of angular pebbles cemented together.
sandstone Sandstone is sand grains cemented together into solid stone.
siltstone Siltstone is made from silt particles cemented together.
Shale Shale is made from silt particles cemented together. It is similar to siltstone but with even finer grain size,

Igneous metamorphic sedimentary rock are the three main types of rock on earth. Read more about Igneous Metamorphic Sedimentary Rock:

Igneous Rocks

Metamorphic Rocks

Sedimentary Rocks

metamorphic rock collection igneous rock collection sedimentary rock collection