§ 2.2.4 Powdery Texture (Helps in Mining and Mineral Processing)
 One of the benefits of dealing with lunar material is that it's powdery on the surface. Indeed, the astronauts compared it to ash. Look at how fine the imprints of their sunken footprints are.
The reason for this is the lack of any shielding atmosphere, which has allowed meteorites, micrometeorites and solar and cosmic radiation to bombard the surface over the eons, pulverizing it into powder. Typically, the thickness of the powder is 2 to 10 meters in the lowlands, and 100s to 1000s of meters (kilometers) in the highlands, the highlands consisting of piles of crater ejecta.
Since the surface of the Moon has been unchanged by any geologic activity for 3+ billion years, we see the accumulated effects of 3+ billion years of meteorite bombardment and pulverization.
As a NASA report summarizes: "The fragmented material consists of as much as 25% by weight under 20 micrometers in diameter [i.e., one fiftieth of a millimeter!], and more than 70% under 150 micrometers in size [i.e., one seventh of a millimeter]. Approximately 90% by weight of the lunar soil consists of particles under 1 millimeter in size." It's more powdery in some places than in others.
The material properties of lunar soil are discussed further in the section on mining.
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