It’s a harsh place, the surface of the moon. NWA 8010 is a lunar regolith breccia meteorite that bears witness to this.
Melt veins are formed by large impacts. The veins in NWA 8010 did not cool instantly into glass. They had time to nucleate along wall rock and crystallize into feathery tufts of very fine laths that grew to meet in the center of the veins.
Apollo 14 and 16 returned with crystalline lunar spherules similar to those in NWA 8010. Researchers believe a large impact was necessary to form not only melt droplets but also a cloud of dust and gas that insulated the molten material from the cold of space and allowed time for crystals to form. Long flight time is inferred by the time needed for solidification and, in the case of Apollo 14, the composition of the spherules differs from the rock in which they are found.
All these photos were taken from the single thin section shown last.
Plane polarized light. Plane polarized light.
