Balsatic Lava
There are three different types of basaltic lava flow. This lava typically flows from spatter cones, scoria cones, fissure systems and shield volcanoes. The different types of flow will produce different surface structures. Pahoehoe lava can have a ropy, billowy or smooth surface. As the lava cools it becomes less fluid and acts like a plastic substance. These lavas are the first to come out of volcanoes. A'a flows are thicker than pahoehoe lavas and move faster. At the front of the flow is a lot of rubble.
Silica Lava
The amount of silica also is used to classify different lava. Basaltic lava has low levels of silica at levels under 52 percent. Andesitic lava contains between 52 and 63 percent silica. Rhyolitic lava contains more than 63 percent silica. The rate of flow is based on the silica content as lavas with low silica have lower viscosity and will flow faster. Lava with higher contents of silica will flow very slowly.
Alkaline Lava
Some lava also can be classified based on the alkaline content. The alkaline content refers to the amount of sodium oxide and potassium oxide. Lava types with mild levels of alkaline include alkali basalt, trachyandesite, trachybasalt, comendite and trachyte. Lava that contains high levels of alkaline compounds include tephrite, tephriphonolite, phonolite and tephrite. Alkaline lavas are typically found near oceanic and continental settings.
Unusual Lavas
Several lavas exist that are unusual and rarely found. Carbonatites contain more than 50 percent carbonite and less than 10 percent silica. There are only 330 sites around the world that contain carbonatites lava. These types of lava erupt at temperatures between 500 and 600 degrees Celsius, a low temperature for volcanic eruptions. Komatites is found in South Africa along the Komati River. This type of lava has more than 18 percent magnesium oxide and a low silica content of between 40 to 45 percent. These are the oldest types of lava as there are no modern lava flows. The youngest komatites lava is 90 million years old.