3M began as a mine for an abrasive that turned out to be worthless rock.
In 1902 five businessmen formed the Minnesota Mining and Manufacturing Company to dig corundum for grinding wheels. The deposit was anorthosite, a low-grade rock worthless as an abrasive. The mine busted, so they pivoted to buying grit and making sandpaper. That failed quarry, its name worn to three letters, invented Scotch tape and the Post-it Note.
3M on Brandseum