Wiktionary
mascon
n. 1 a region within a solid astronomical body that is of higher density than the surrounding material 2 A Lunar mare that has a greater density of rock than the surrounding area
Usage examples of "mascon".
Moon: using a device that sent radio impulses into the body of the Moon to see whether any ice or water existed below the surface, and conducting a fascinating experiment which might help to decide a furious lunar debate: Are mascons merely impacted meteors, suggesting that the Moon had a cold origin, or are they submerged lava flows, indicating a hot origin?