An Ottawa coin collector has written a book on Canada's most exotic pre-Confederation coin, the P.E.I. "holey dollar," being released at the Toronto Coin Expo this weekend.

In 1813, the government decided to "make" its own coins. But instead of minting them, the acting colonial governor on P.E.I. at the time, William Townshend, instructed that all common Spanish American silver dollars have holes punched in them, thus creating two coins from one.

The outer ring was worth five shillings, the inside "dump" was worth one shilling.

Two centuries later, little information remains about the rare P.E.I. Holey Dollar. But collector and Carleton University professor Chris Faulkner has spent the last 20 years researching them, and he's written a book on one of the country's most exotic coins.

"The whole idea that somebody would punch a hole in a coin, and make two pieces out of one, and have them circulate in some local place, but using a foreign coin in order to do that," said Faulkner.

"That's attractive to a lot of people, so I mean these P.E.I. holey dollars, they're actually collected by people all over the world."

Faulkner will be launching his new book, The Holey Dollars and Dumps of Prince Edward Island, this weekend at the Toronto Coin Expo.

The coin is valued at about $5,000.

Faulkner said he has identified about 79 holey dollars worldwide, including his own.