Rock Types

The Moon's surface is primarily covered with igneous rocks. The lunar highlands consist of anorthosite, an igneous rock mainly composed of calcium-rich plagioclase feldspar. The lunar maria, on the other hand, are layered with basaltic lava. 

1. Igneous Rocks:

Basalt:

Formation: Basalt rocks on the Moon are formed from cooled and solidified lava.

Appearance: They are usually dark-colored rocks.

Occurrence: These rocks are abundant on the lunar maria, the dark plains on the Moon's surface.

Anorthosite:

Formation: These are composed predominantly of a type of plagioclase feldspar and are formed from the slow cooling of molten rock.

Appearance: They are generally light-colored rocks.

Occurrence: These rocks are found in the lunar highlands.

2. Metamorphic Rocks:

There are not many true metamorphic rocks on the Moon, but some rocks have undergone processes that are somewhat similar to metamorphism.

Impact Melt Rocks:

Formation: These rocks are formed when the heat from meteorite impacts melts the lunar surface rock.

Occurrence: Found in and around impact craters.

3. Sedimentary Rocks:

The Moon doesn’t have true sedimentary rocks like Earth does. Earth's sedimentary rocks are formed from the accumulation and cementation of mineral and organic particles, often involving processes with water, air, or living organisms, which are absent on the Moon. However, there are rock fragments and dust particles that accumulate on the lunar surface.

Regolith:

Formation: A layer of loose, fragmented material that covers the lunar surface. It’s formed by the impact of meteoroids bombarding the Moon.

Occurrence: Covers the entire lunar surface.

Summary:

Igneous Rocks: The primary type of rocks found on the Moon, including basalt and anorthosite, formed from cooling molten rock.

Metamorphic Rocks: Not common on the Moon, but some rocks, like impact melt rocks, have undergone changes due to the intense heat from meteoroid impacts.

Sedimentary Rocks: The Moon lacks true sedimentary rocks but has a layer of regolith, consisting of broken rock fragments and dust.

Each of these rock types and processes provides insights into the Moon’s geological history and evolution.