I have noticed that the flint rocks that I pick up have the smooth brown outer crust on them. I think that this happens over a long time but Im not sure how long. I have seen TV programs that show artifacts that are 50,000 years old and they dont have this brown crust on them. So the first question is how long does it take for a piece of flint to git this smooth brown crust on it or is it formed this way? The first picture below shows ordinary flint rock as I pick it up with no particular shape. The rest of the pictures show a piece I picked up yesterday that actually has the shape of a large hand ax or somethin like that. It also has the smooth brown crust but the crust is thin and you can tell easily that the rock is made of flint unlike others where the crust is thick enough that if you dont know what you are lookin for you wouldnt know that it is flint. If my piece is worked flint then it must be the oldest artifact ever found. And it came from North America not Africa. How old is this worked piece of flint or is it worked at all. Some one tell me somethin before I go wackin on it tryin to make an arrow head.
Thanks for any help
Marshall

I'll give it a whirl.

The lower piece is definitly worked by man ! Maybe started as a core then slightly trimmed to finish out as a chopper. That one edge on view shows the classic "shattered " look flint gets from straight on pounding. Age cannot be determined from the exterior patina of man modified flint. Your chopper may have had a bit of time in a drainage since none of the flake lines are sharp.

What mother nature does to minerals [ including fossils ]is almost limitless, probably to keep reminding mere mortals to keep on their toes.

In brief, All flint started as a relatively soft creature MILLIONS of years ago. Giant sea sponges
account for a vast amount of the material we see. [ smaller creatures do not occur in large quantity ]
The exterior appearance starts to form the minute the creature keels over and is rolled in the sea bottom oooz ! Whatever the consitancy and what was on the bottom will stick, Thats too simple for Mom nature, now comes modification from depth pressure, mineral in overlaying soils and finally. . . For those lenses that become exposed near the surface, they break in random ways from the seasonal hot and cold expansions.

Local conditions rule, thats why the folks on the Edwards plateau made so few Kerrville knives, they didnt have the vast number of perfect nodules available to the guys in down town KerrV.