How hard is the Lunar surface?

The lunar surface visible to us is mostly regolith - space dust, asteroid remains, and what-not. The true lunar surface is below - at depths ranging from a few inches to a few metres.

Given that Luna survived the impact which created Oceanus Procellarum it may be as hard as bedrock. How hard is the Lunar Surface?

• The question basically asks for the properties of bedrock. Some samples taken during Apollo 15 and 16 are as close as one can get in terms of actual rock properties. However, it is still argued, whether this was actually bedrock or still part of the bombarded upper layer of the lunar surface. More interesting and less arguable results come from seismic measurements. As long as there is no Geoscience.SE, I would like to give an answer to this question. Aug 23 '13 at 16:50
• Even being on topic, this is an extremely broad question. I'm still not completely convinced it should stay opened... Aug 30 '13 at 16:04
• nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1967-112A-04 This is a nasa experiment too, not sure of the results
– user106
Oct 1 '13 at 12:53
• link.springer.com/article/10.1007%2FBF00561845#page-1 bearing strength has also been measured, but the paper is paywalled
– user106
Oct 1 '13 at 12:54

I assume you mean the density of the lunar surface, which itself is made up of a few different rocks, the densities of which I analyse below:

Cosmo Sparks have a short article around the topic of the densities of lunar rock. If we compare that to the densities of Earth rocks, we should be able to come up with a rough estimate as to how hard the rocks are.

Some important quotes from the article rate the density of moon rocks to be:

The seven mare basalts range in grain density from 3270±10 to 3460±50 kg/m3

and

The four feldspathic highlands rocks range in grain density from 2840±10 to 2910±10 kg/m3

and also

Grain densities of the two impact breccias are 3030±30 and 3050±10 kg/m3

Converting these to g/cm3 for the sake of ease of use gives us:

Lunar rock          Grain density
─────────────────────────────────
Basalts:            ~ 3.365 g/cm³
Highland Rocks:     ~ 2.875 g/cm³
Breccias:           ~ 3.040 g/cm³


A quick check for densities of Earth rocks in g/cm3 gives us:

Rock             Density (g/cm³)              │             Rock             Density (g/cm³)
­­­­­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─┼­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­─­­
Andesite              2.5 - 2.8               │             Limestone             2.3 - 2.7
Basalt                2.8 - 3.0               │             Marble                2.4 - 2.7
Coal                  1.1 - 1.4               │             Mica schist           2.5 - 2.9
Diabase               2.6 - 3.0               │             Peridotite            3.1 - 3.4
Diorite               2.8 - 3.0               │             Quartzite             2.6 - 2.8
Dolomite              2.8 - 2.9               │             Rhyolite              2.4 - 2.6
Gabbro                2.7 - 3.3               │             Rock salt             2.5 - 2.6
Gneiss                2.6 - 2.9               │             Sandstone             2.2 - 2.8
Granite               2.6 - 2.7               │             Shale                 2.4 - 2.8
Gypsum                2.3 - 2.8               │             Slate                 2.7 - 2.8


So comparatively, on the Moon:

• Basalts are of similar density as Peridotite

• Highland Rocks are similar to many Earth Rocks, of strong similarity to Dolomite

• Breccias are similar to a dense Diabase, Diorite or Basalt on Earth

If you instead meant the bearing strength of the lunar surface there is a paper on this, which is unfortunately paywalled: http://link.springer.com/article/10.1007%2FBF00561845#page-1

• Hardness is not bearing strength or density. Oct 21 at 6:02

The rocks on the surface of the Earth are formed by the sedimentary (because of the erosion of the rocks by the water and the atmospheric winds) while in the moon it is only igneous ("fire-formed rocks" which are not eroded by anything since it has no atmosphere) so it must be so hard when compared to that on earth

Source

The bulk density of the Moon is 3.4 g/cc, which is comparable to that of (volcanic) basaltic lavas on the Earth (however, the bulk density of the Earth is 5.5 g/cc, because of the dense iron/nickel core). The Moon is coverered with a gently rolling layer of powdery soil with scattered rocks that is called the regolith; it is made from debris blasted out of the Lunar craters by the meteor impacts that created them. Each well-preserved Lunar crater is surrounded by a sheet of ejected material called the ejecta blanket.

1.The Maria are mostly composed of dark basalts, which form from rapid cooling of molten rock from massive lava flows.

2.The Highlands rocks are largely Anorthosite, which is a kind of igneous rock that forms when lava cools more slowly than in the case of basalts. This implies that the rocks of the Maria and Highlands cooled at different rates from the molten state and so were formed under different conditions.

3.Breccias, which are fragments of different rocks compacted and welded together by meteor impacts, are found in the Maria and the Highlands, but are more common in the latter.

4.Lunar Soils contain glassy globules not commonly found on the Earth. These are probably formed from the heat and pressure generated by meteor impacts.

The Anorthosites that are common in the Lunar Highlands are not common on the surface of the Earth (The Adirondack Mountains and the Canadian Shield are exceptions). They form the ancient cores of continents on the Earth, but these have largely been obliterated by overlying sedimentary deposits and by plate tectonic activity.

External source

http://en.wikipedia.org/wiki/Moon_rock