You have probably spent your life laboring under the misapprehension that all chalk is the same. Chalk — you know, the dusty white sticks you use to write on a chalkboard? Chalkboards — the thing they used in classrooms before the 1990s to visually demonstrate the subject matter being discussed in class? It's possible you missed that particular period of history.
Which might be why you've probably never heard of Hagoromo Fulltouch Chalk — unless, of course, you're a mathematician. Chalkboards have been disappearing from educational institutions for decades, but math is possibly its last stronghold. Mathematicians prefer writing complex theorems in chalk than with a whiteboard marker or a smartboard. And Hagoromo chalk has been described as the "Rolls-Royce of chalk."
Founded in 1932 in Nagoya, Japan, the company that became Hagoromo Bungu barely survived WWII, but went on to produce 90 million sticks of chalk a year by 1990. By this time, mathematicians from all over the world coveted the product. According to chalk connoisseurs, it's dense and difficult to break, produces very little dust, writes more smoothly and erases more cleanly than any other chalk in existence.