Mariah Carey shocked fans on Wednesday when she announced she is releasing a new album, "The Rarities."

The five-time Grammy Award-winner, who is the bestselling female artist of all time, gave superfans an idea of what to expect from the upcoming project, out Oct. 2, during an appearance on "Good Morning America" on Wednesday.

"I found stuff in my vault that I had either started to work on a long time ago and never released or that I wanted to kind of finish mixing," she said. "There are songs that have previously not been released, so it's exciting."

"It's a monumental occasion for my career. Being in this business for two years is really tough but somehow we've lasted," she joked.

The two-disc album will feature unreleased, never-before-heard recordings Carey created from 1990 through 2020.

"Rarities" will also allow fans to hear songs from Carey's "Live at the Tokyo Dome" performance, which was her first concert performance in Japan during her 1996 world tour.

The singer also has another exciting project, an upcoming memoir, "The Meaning of Mariah Carey," out Sept. 29. She described the project as "a labor of love."

"There are a lot of very personal stories about my childhood ... those are difficult but very cathartic as well," she said. "The cool thing about this project is that there are songs that I talk about writing or recording even as a little kid, starting as a little kid, until now that I've found in the vault."

"We're kind of putting this out at the same time, and I don't want to give away too many titles or anything but it's exciting because they're kind of merged together in a really organic way," she added about the timing of the book and album releases.

She said fans will get a look at her upbringing and get to know her like never before in the new memoir.

"I haven't really ever been able to do an entire book where I felt comfortable to really talk about issues that I went through growing up as a kid and just starting out so young in the industry," she shared. "It's been an interesting journey, and I hope that people will get a better understanding and actually enjoy reading the book and listening to the 'Rarities.'"

For the Lambs who can't wait for the upcoming album or book release, Carey is also releasing a new song, "Save The Day," on Friday.

She didn't give much away about the song but said there will be a charitable component attached to it.

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