In my catalog I see it's an Easton EC70X fork on the Kona JTS. If I get the meaning in the letters of Easton forks right it's the 'E' for Easton, the 'C' for Carbon and the 'X' for Cross. So then it would be a carbon fork (looks like one on the picture, too).
That's what they sell in Germany, don't know if the set-up is different in the US.
Addition: It also says it's a carbon fork in the catalog, I was just too slow reading it.