An axe but how old?

[mastereagle22]

Obviously this is an axe head. What is not obvious to me and my sis who found this is how old and how to clean it up a little to get a better idea.

She and her husband found it in a location where a church had been burned down during a CW battle. She said it was between 10 and 12 inches deep and took them a little bit of time to get it out. They were using their X-30.

Any help would be great. Sorry bout the pic but I only had my Razor and couldn't get a better pic.

The quarter is to help indicate size, it was all I had and I placed it on the item.