Igneous Rocks

Pumice rock

Pumice

The pumice rock is the lightest rock in the world and is the only rock in the world that can float in the water. It can float in the water because of the special way it was cooled. The pumice rock cooled very fast therefore it is very light and that it also cooled underwater that causes the holes in the rock. People use the rocks for rubbing of dead skin from their feet. It looks a bit like coral. It has a very rough texture and that’s why they use it to rub off dead skin. Pumice is also used as insolation or as a hand soap ingredient.

Granite

GraniteGranite as said before is similar to marble and is also used for kitchen countertops and floors or statues. Granite is the most used rock for everyday life for example most buildings have granite in it. A lot of pebbles on the ground are granite. Like marble it is cooled very slowly and has almost the exact same sized crystals as marbles. Granite is the most common rock on the earths surface. Granite has a pretty rough texture. People sometimes use granite for rock climbing walls.

Basalt

Basalt

Basalt is very smooth and hard rock that is made when volcanoes spit out pieces of lava. Basalt is also very common on the earths surface like granite but is the most common rock underground. Basalt has very small crystals so it cooled very quickly but not as quickly as pumice which doesn’t have crystals at all. Basalt can be found on the Moon, Mars and even Venus. Since Basalt is very hard people used to very often use basalt as a grinding stones for mills to make wheat out of grains. Basalt is very often used for asphalt.

Obsidian

Obsidian

Obsidian is a very smooth and shiny rock that is also known as natural glass. A lot of people used to use obsidian to make arrowheads or fishing hooks because it can be very sharp. A lot of surgeons today use obsidian knives for eye surgery or other things. The stone aged people often wanted obsidian because it was sharper than flint and was very practical back then. Obsidian also cools very slowly so it has few crystals even though it is very shiny. Obsidian is very brittle and therefore can be chipped very easily, which is why the stone aged wanted it. Obsidian sometimes come very rarely colored blue, yellow, red or orange.

Scoria

ScoriaScoria is a red, brown, or black and is also referred to volcanic rock. Scoria was cooled a bit slower then pumice but also underwater that is why it has holes in it like the pumice rock. The name scoria comes from the Greek and means rust, probably because it can be red as rust as seen below in the picture. Scoria is often used in high temperature isolations, and landscaping and drainage works. Some statues on Easter Island have scoria in them.

Facts

Facts

• Igneous rocks are the most common rocks used for buildings• Mount Rushmore is made out of igneous rocks• The word igneous comes from the Latin and means fire,

because igneous rocks come from volcanos.• Did you know that basalt which is an igneous rock is one of

the heaviest and densest rocks in the world.• Did you know that most of the Empire State Building is made

of igneous rocks.• Thousands of years ago people carved their homes out of soft

igneous rocks.

Hope you learned something!By:

Giulia, Julia and Patrick