Analysis of information sources in references of the Wikipedia article "Cobblestone" in English language version.
In fact, Belgian block refers not to the type of stone but the way it is cut: in rectangles. People often refer to roads paved this way as "cobblestone streets," but that isn't strictly correct. Cobblestones are rounded, typically because they've been worn smooth by rivers. They might be hell to drive on, but they were cheap: you could just dredge them up from the river...
In fact, Belgian block refers not to the type of stone but the way it is cut: in rectangles. People often refer to roads paved this way as "cobblestone streets," but that isn't strictly correct. Cobblestones are rounded, typically because they've been worn smooth by rivers. They might be hell to drive on, but they were cheap: you could just dredge them up from the river...