Volcano
This page is about the specific entity named Volcano. For the general grouping of entities sometimes referred to as Volcanoes, see Geyser.
The Volcano is a Geyser which irregularly produces large amounts of extremely hot Magma.
Taming
Due to the extreme temperatures involved, taming a volcano requires high melting point materials not only for machines, but for tiles.
Extracting material
The viscosity of Magma can be exploited to only have a small trickle exit the volcano chamber at a time. Magma will not flow further than ten tiles horizontally, and will not gain enough pressure to move up a U-bend, so outflow can be controlled by simply building a ten-tile, one-tile-high passage with a Mechanized Airlock at one end. To most efficiently extract material, have the tiles below the tenth be steel Mesh Tiles - if debris would form inside a mesh tile, it will instead search the adjacent tiles, including diagonals, which can eject debris into a Steam chamber while still keeping liquid magma and the volcano itself in a safe Vacuum environment.
As a heat source
Volcanic Magma is hot enough to melt most Metal Ore into the corresponding Refined Metal, meaning that a volcano can be used as an early substitute for a Metal Refinery. Its renewable nature also makes it a potential source of heat for Petroleum boiling. It is also technically possible to use volcanic lava to produce Molten Glass from Sand, though only in a very small range before the magma becomes too cold.
As a power source
Tapping magma for power is more involved than simply using its heat. For the best results, a Steam Turbine requires its input steam to be 200 °C or below; this generally requires two separate steam chambers, one of which stores heat and debris from the volcano, while the other is connected to it by solid tiles and a Mechanized Airlock, set to close when the temperature in the turbine room falls below a set threshold.
Dropping the igneous rock output to 200 degrees produces an average of about 1680 kDTU/s across its entire life cycle, which can be handled by two actively cooled turbines.