Forbes What could cause orange soil on the Moon, perhaps the most featureless of all the large, airless rocks in our Solar System? by Ethan Siegel
'What the analysis back on Earth revealed was fantastic: this was volcanic glass. What occurred was that molten lava from the interior of the Moon erupted, some 3 to 4 billion years ago, up above the airless surface and into the vacuum of space. As the lava became exposed to the vacuum, it separated out into tiny fragments and froze, forming tiny beads of volcanic glass in orange and black colors. (The tin in some of the fragments is what gives the orange color.)
'Over the decades after the Apollo missions concluded, technology continued to advance. In 2011, a team was able to analyze the samples that Schmitt and Cernan brought back, and found something spectacular: evidence that water was included during this volcanic eruption. The glass beads, based on the dryness of the Moon, should have had water concentrations of no more than 1 part-per-million (ppm), but instead exhibited water concentrations some 50 times as great. Moreover, there are olivine inclusions identified by the recent analysis, showing the presence of water in up to ~1,200 ppm concentrations.
'That number is important to someone who’s a geologist, because it’s the same concentration of water as rocks found in Earth’s interior! In other words, if you ever doubted that the rocks from the Moon and the rocks from the Earth came from the same place, now there’s even an extra piece of evidence: from the water inclusions found in ancient volcanic material on the Moon.'