Chains on ice

Having grown up in Northern Idaho before the use of magnesium chloride, I would have to say that the term "Black Ice" was not to identify the content or the ice, but rather because it was often hard to discern whether or not you were driving on pavement (black), wet roads (also black), or a very thin layer of ice that might appear to be just wet (also black). Watching for any spray off of tires became a tool for trying to determine what one was driving on.

 

yes black ice is ice that looks like bare pavement, a ice covered road that looks like its covered in ice is a icy road

 

i.e. precipitation that was liquid (or turned to liquid) on the road, before [re]freezing. [it was never frozen (sleet, or snow, or grapple) before hitting the surface]