Flint!

This rock appears to be a type of chert, specifically a variety known as flint. Flint is a hard, sedimentary cryptocrystalline form of the mineral quartz, categorized as a variety of chert. It often has a glossy appearance when polished and can exhibit a range of colors, commonly grey, brown, or black, with some yellowish or reddish inclusions. The texture and coloration in your rock, along with its somewhat waxy luster, are indicative of flint.