Geological Chronicle
Located in the southeastern part of the Moon adjacent to the craters Hommel and Rosenberger, Vlacq is an impact crater measuring 89.21 kilometers in diameter. Because of its location, the crater appears foreshortened when viewed from the Earth. Dating to the Pre-Nectarian epoch, it has become eroded, though not to the degree of its larger neighboring craters. The crater is named for Dutch mathematician Adriaan Vlacq.
Several satellite craters mark the perimeter of the formation. Along the southern edge, Vlacq G intrudes into the southern rim and is overlaid in turn along its southwest rim by the sharp-rimmed Vlacq B. On the opposite side, the satellite crater Vlacq C is attached to the northeastern exterior rim of Vlacq.
The interior floor of Vlacq has been resurfaced by lava, leaving a nearly level base, though ejecta from nearby impacts overlays the southwest half. In the midpoint of the floor is a rounded massif roughly 15 kilometers in length along the northwest direction. Spectral observations have identified pure crystalline plagioclase on this central peak. Tiny craterlets dot the floor alongside several ghostly crater remnants in the western half, most notably a circular depression to the west of the central peak.