Here's why:

* Moon's density: The Moon has an average density of about 3.34 g/cm³.

* Earth's crustal rocks: The Earth's crustal rocks have an average density of about 2.7 g/cm³.

Therefore, the Moon is slightly denser than the Earth's crust. This difference in density is due to several factors:

* Composition: The Moon is composed primarily of silicate minerals, similar to Earth's crust, but also contains a significant amount of iron.

* Internal structure: The Moon has a smaller iron core compared to Earth, which contributes to its lower overall density.

While the Moon and Earth's crust share some similarities in composition, the difference in density is a significant factor in their distinct geological evolution.