This is an old thread that's been bumped, but some answers are nevertheless useful for future reference.
They are not official legal tender coins of Liberia. They were struck by a private mint in America without the knowledge or consent of any recognized government in Liberia (Liberia was in the middle of a civil war at the time, so it was kind of hard to check). As such, they are not technically "coins", so they are listed in the "Unusual World Coins" book rather than the mainstream coin catalogues. They are cupronickel; zero silver content. Nevertheless, they are not completely worthless; the UWC book lists them at $10-$12 each.
Here's the NGC entry for the Oath coin.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis