My interest began when I visited the Heavener stone while on a trip as a teenager. Back in those days (mid 70's) you could go right up and touch the stone in person. Now, so I'm told, it's encased in some sort of glass contraption which prevents close analysis by the general public. :(
What is not mentioned here is that there was at least one more similar stone found in the hills adjacent to the Arkansas River, in the Tulsa vicinity. Tulsa is about 150 miles to the north of Heavener. The location of these stones, according to the newspaper article I read at the time (ca. 1980) was kept secret to prevent vandals from damaging them. Apparently they're too big to move easily.
The thought is that these same Viking explorers were traveling up the Arkansas sometime around 800 A.D.
Cool stuff.