What is a rock k-12 question for best answer

The solid mineral material forming part of the surface of the earth and other similar planets, exposed on the surface or underlying the soil or oceans.

The solid mineral material forming part of the surface of the earth and other similar planets, exposed on the surface or underlying the soil or oceans.       1. Igneous rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava. 
2.Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles (detritus) to settle in place.
3.A metamorphic rock is a result of a transformation of a pre-existing rock. The original rock is subjected to very high heat and pressure, which cause obvious physical and/or chemical changes. Examples of these rock types include marble, slate, gneiss, schist.

Since wxyz is 4, halfof that would be 2.