I have a samarium cobalt magnet stuck to my refrigerator that I got from The Foxboro Company when I was coop student there in 1994. It was part of a differential pressure sensor they made that Dutch Oil and others used to measure flow of oil and gas across their empire. A thin wire vibrating in a magnetic field varied frequency as the tension between the sensor diaphragms varied with differential pressure. The frequency was converted to 4-20mA signal for process control. All analog, very precise. This is how we got to the moon girls and boys! The magnets weren't cheap. My magnet has a tiny chip in one edge, so it was rejected and given to me by the engineer that invented and patented the vibrating wire sensor technology. My favorite job evah! and a treasured possession. It's not really suited for refrigerator duty, it sticks too hard.
![Very Happy :D](https://www.audionervosa.com/Smileys/default/icon_biggrin.gif)
It was made with California Cobalt, not chinese. But China did the same to our rare earth mines as they did to our steel.