How much of the earth is rock?

Although sedimentary rocks are estimated to comprise only 5% of crustal rock, 75-80% of the land surface is covered by them.

yes it is

Basalt is the most common rock thought of as a link in lithology between the Earth and the moon.

Composition, mainly. In particular our Sun has a signature emission of iridium isotopes which can be seen throughout the earth's geology and which is not shared by objects from without the solar...

Me personally?. Alot..