The material ejected out of a volcano falls into three types: solid, liquid and gas.
Solid Material. When volcanic material flows out of the vent of a volcano it carries with it broken pieces blasted from the old rocks lying in its route. These pieces are small as well as large. Small pieces are also found along with large sized pieces. The molten material shoots into the sky at the time of explosion. When this material comes down it becomes cool and solid. If the diameter of a piece is more than 32 mm., it is known as volcanic bomb or blocks. The pieces which range from 4 to 32mm in diameter are known as Cinders and smaller pieces are called ash particles.
Liquid Material. The liquid material that is ejected from a volcano is called Magma. As soon as the magma comes out of the volcano, it is called Lava. The temperature of lava is very high. This is why it appears red or white but when it is cooled it appears dark. Lava besides being ejected out of crater also comes out of secondary cones.
Gaseous Material. Many types of gaseous material come out of a volcano Stream are the major constituents of the gaseous material. A part of the steam is obtained from the water which is neither underground nor above the land surface. Water which comes in contact with hot gaseous material is converted into steam. Hydrogen present in the gaseous material of the volcano combines with the oxygen of the atmosphere and forms steam. Water mixed with magma situated at a great depth is also thrown out, along with the ejected magma. The water is called Juvenile water.
Carbon dioxide comes next to water. Sulphur in vapour form is also ejected. It produces poisonous gases when it combines with other gases. Gases like Chlorine, Fluorine, etc., are also emitted in large quantities. A very useful element, Boron is also ejected along with gaseous material.
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