Three types of volcanic materials are distinguished as Liquid, sold and gaseous materials.

1. The liquid material: Lava is the most important liquid material ejected by volcanoes. The molten rock material is called “Magma” below other earth’s surface, while it is called lava when it reaches the earth’s surface. There’are two main types of lava-acid lava and basic lava.

2. Solid materials: It consists of volcanic dust, volcanic ash, cinder, volcanic bombs and large angular fragments. The finest particles thrown out by volcanoes are called ‘volcanic dust’. They are grey in color and very light in weight. The molten lava shoots up to the sky at the time of explosion.

Then it cools and solidifies into round mass before falling to the earth. It is called “volcanic bomb’. Small lava fragments are thrown out by a volcano during eruption and are known as “lapilli or pumice’. These are angular in shape and as big as finger joints. The smaller fragments of lava smaller than lapilli are like peas and are called “volcanic ash” or ‘Cinder’. The solid angular fragments which are bigger than lapilil are known as ‘Breccia’.

3. Gaseous Material: A variety of gaseous mixture comes out of a volcano, accompanied by liquid and solid materials, e.g. Vapour, hydrogen, carbon dioxide, sulphur, ammonium chloride etc. But vapour or steam is the most important. Sometimes huge amount of steam is thrown out to form dark clouds above the crater, like a ‘cauliflower’ in shape, it may bring heavy downpour of rain.