The Book Receptacle is used to activate a Portal allowing a player to link to other Ages.
The Book Receptacle is crafted like a chest, but with Crystal blocks.
It can be placed by looking at a Crystal block and right-clicking.
The Book Receptacle functions like a Linkbook Stand, because it will hold a book in it. The difference is that it is much easier to remove a book from it: simply right-click it with at least one free inventory slot. When the book is removed, the Portal will close.
For people who are interested how the Book Receptacle works when opening a Portal, look at the Portals page.