A seismometer was also set up to record tremors caused by meteorites or by volcanic eruptions. Finally, a laser reflector was aimed toward Earth to reflect a beam of light directly back. This experiment would allow scientists to measure the time it took for waves to travel to the moon and back. There is evidence of volcanism in the past and maybe still today The moon has a surface crust and a molten or at least partially molten interior like Earth. The core might consist of nickel or iron.
Lunar soil is probably igneous rock, meaning formed by lava.
The soil is interspersed with glassy material possibly from vaporization and cooling of material hit by meteorites. The surface is approximately 3.5 billion years old. 60 elements were identified by flame tests. Rocks are deficient in sodium and potassium but rich in titanium. There are radioactive particles of helium, argon, neon, krypton, and xenon present from the solar wind.