When a volcano erupts, a large amount of gas (mainly water vapor) is ejected. Under huge pressure, a large amount of powdery, granular, clumpy and other debris fly out from the crater, most of which are scattered on the volcanic cone. Nearby, these are all ejections.
Volcanic ash
   The hot gas blows the magma material into a powder, which is black-gray volcanic ash. On the southern slope of the Laohei Volcano volcanic cone, volcanic ash, volcanic sand, and volcanic gravel are produced together.
Volcanic sand, Lapilli
    The natural colors of volcanic sand and volcanic gravel are yellow, brown, black, needle-like, foamy or granular, and light in weight. The particle size is mostly less than 3 cm, mainly 0.2 to 2 cm.
    The reason is that the molten magma material in the magma lake is blown by the released hot gas into foamy, granular particles flying into the air, like rain, scattered on the volcano cone and near the slope foot. Volcanic sand and volcanic gravel are mostly found on the outer slopes of the volcanic cones in the area, especially on the southern slope of Laohei Volcano. The local area is red and pink, and it is produced in the shape of a nest. It is because the fallen volcanic sand and volcanic boulders are baked by the high-temperature gas ejected from the cracks in the lower part.
Volcanic bombs
    The molten and semi-plastic lava in the magma lake is thrown into the air to rotate, twist and fall to the ground under the action of gas. It has various shapes, such as egg-shaped, bread-shaped, twist-shaped, spindle-shaped, strip-shaped, etc. It is mostly black, with turtle cracks on the surface, and honeycomb-like inside, which is easy to weather and break; some are dense and heavier. Volcanic balls are mostly produced on volcanic cones and at the foot of slopes, and less far away from volcanic cones. Volcano balls vary in size with a larger diameter of up to 3 meters, and a smaller one is about 10 cm. The general size is 0.2-0.5 meters. Ejections of basement rocks can also be seen, such as granite, mud stone, sandstone blocks and their inclusions wrapped by magma. Some volcanic balls are covered with volcanic sand and gravel after they hit the ground.
Pumice
    It is mostly black, but purple-red and brown are also visible. The round or oval stomata are extremely well-developed and have a honeycomb shape with light weight, which can float on water. Most of them are produced in the form of lumps, and the diameter of the lumps is generally 0.1 to 0.3 meters, and the larger ones can reach 1 meter. It’s produced at the foot of volcanic cones and slopes. The formation of pumice may be due to the rich gas in the magma lake. The freshly solidified (or semi-plastic) lava is rich in gas and has particularly developed pores, so it is particularly light. Later, it becomes a rock from the volcano under the action of the gas ejected. It is thrown from the mouth and falls on the cone of the volcano or at the foot of the slope. Some pumice is also formed by volcanic bombs with developed pores and fragmentation of lava cakes.
Lava pies and agglomerates
    Under the action of gas, large pieces of molten magma are thrown out from the magma lake, and fall on the crater and cone. Under the action of gravity, it can slide down a short distance to a low place with over tens of square meters. Its output state resembles overflowing lava flow, which can be called thrown out lava flow, and the shape looks like a pie after it hits the ground. The difference between it and the volcanic balls and pumice is that the latter no longer flows after being thrown to the ground, and the individual is small (generally less than 3 meters), and the lava cake is still molten after it hits the ground, with plasticity and fluidity. Lava pies can cement and fuse the ejected objects first to form rocks such as agglomerates. Some agglomerated rocks are formed by high-temperature sintering of massive projectiles such as pumice, and are mostly red.