This has been a controversial topic ever since Neil Armstrong took those famous first steps on the Moon back in 1969. Now rather than discuss the conspiracy and ‘hoax’ theories that are always put out there I figured I’d go ahead and give a ‘rock persons’ point of view on the matter.
For starters common minerals which we find here on Earth such as: Quartz (abundant in sandstones), calcite (Limestones), micas (slate), hematite (a form of iron oxide…pretty much what makes up rust) and amphiboles (found a lot in volcanic rocks) are rare or not found on the Moon. Whereas the mineral anorthite (a calcium rich plagioclase feldspar mineral) which is extremely abundant in the white areas you can see on the Moon’s surface, yet here on Earth it is rare and limited to rocks older than 500 million years. A huge comparison between the Earth and the Moon is that no hydrous minerals (water containing minerals) have been found on the Moon as of yet.
Apart from minerals in the rock how can we tell the rocks are from the Moon? In the case of lunar meteorites, like all meteorites that fall to Earth, as they enter the atmosphere they start to burn up which leaves them with a fusion crust (a thin burnt crust). So in places like Antarctica they can be distinguished from terrestrial rocks. Ah! But how can these lunar meteorites be distinguished from other meteorites you say? Well, non-lunar meteorites are usually magnetic or at least contain much more metal than lunar meteorites, and so are more magnetic. Meteorites usually contain nickel and iron metals whereas lunar rocks contain less than 1% metals. Some lunar meteorites do contain much more metal but not enough to be considered magnetic.
Furthermore, all lunar rocks (Apollo, Luna and meteorites) have a significant amount of microscopic craters (<1mm) which they received on the surface of the Moon. This is because of the millions of micrometeorites that hit the Moon each day. That’s right ‘baby’ meteorites. Here on Earth these micrometeorites don’t get a chance to hit the surface as they are too small and end up fully burning up in the atmosphere. We still see their effects but we see them as shooting stars. The Moon doesn’t have an atmosphere to protect it so we see the aftermath of all those tiny impacts within the surface rocks. Impacts to the Moon also cause material on the surface of the Moon to melt producing glass and bits regolith (technical term ‘agglutinites’). If the Apollo, Luna and lunar meteorites originated from Earth, these bits of glass would be broken down in the terrestrial environment in a matter of 200 million years, which is not what we see.
Rocks that were brought back from the Apollo 17 mission are around 4.4 billion years old which is much older than anything dated on the Earth. And not only do we have these great rocks to study for ourselves but now thanks to the Lunar Reconnaissance Orbiter (LRO) we have some fantastic pictures on the Apollo landing sites to provide evidence to the doubters.
So it seems to be a unanimous decision from geoscientists that have studied samples from the Moon, that these are in fact the genuine article. The Apollo rocks are just the same in chemistry and composition to lunar meteorites. Still think they’re faked? Well it would be just too difficult to replicate the story we can get from these rocks. They are so unique that it would be easier and cheaper to go to the Moon and get them anyway. Even people that have been studying lunar rocks for 40+ years agree.