What are the most expensive rock on earth?
The most expensive computer is made in Japan. It is an Earth simulator costing over $400,000,000, which makes it the most expensive computer ever built. This very expensive computer is used for a variety of international projects. Most are related to atmospheric, climate, and oceanographic simulation.
The earth is made of rock. It's sometimes called the lithosphere, and litho means rock. A lot of the rock in the middle of the planet is molten, but liquified rock is rock just the same. The earth has an atmosphere, but it is not a "gas planet" in that sense. We look at the structure of the earth in geology and geophysics. And most folks associate geologists with rocks.