Lava Planet

A Lava Planet is a silicate terrestrial planet covered mostly or entirely by lava. There are a number of factors which could lead to the formation of a lava planet, including: It is impossible (or at least extraordinarily unlikely) for lava planets to be habitable, as their environment and formation almost certainly preclude life. However, if they were somehow cooled, they could conceivably be terraformed.
 * Young protoplanets are typically lava planets due to the intense internal heating effects of a planet too young to have cooled down and intense bombardment of asteroids or comet.
 * Giant impact events, such as the Theia Impact, could also transform a planet into a lava planet.
 * Planets which orbit very close to their parent object may have their surface melted by intense radiation and tidal forces and will hence become lava planets.
 * Planets with incredibly large amounts of volcanism, dubbed as "super-Io" planets after Io, may be lava planets if they orbit very close to their star.

Lava Planets may exhibit the evaporation and condensation of rock, leading to pebbles raining from the sky.

Examples may include COROT-7b and Kepler-10b.

Worldbuilding in Practice
Orbiting the blue giant Hrimnir is a tiny planet Gullveig. Orbiting at a mere 2.66 AU from the centre of the star (whose own radius is about 1 AU), it is bathed in immense radiation. Tidally locked, its day side is heated to an incredible 5200 K, which is almost as hot as the surface of the sun. The planet is completely covered in magma due to the incredible temperatures to which it is exposed. Because of the logistical nightmares colonising and exploiting the planet would entail, it has largely been ignored by corporations and governments before, but scientific studies has shown that the planet Gullveig due to intense heat, it produces lots of rare mineral. Which include a kind of metal that can stay in solid form in enormous temperatures. The nearby civilisations are starting to use the rare mineral to create super anti-heat mining machines to collect other rare minerals.