Chiseled Bookshelf

Chiseled bookshelves are blocks that can hold books, books and quills, written books, and enchanted books.

Breaking
Chiseled bookshelves can be destroyed with any tool, but an axe mines it the fastest. When broken, all contained books are dropped as items. The block itself drops only when broken using a tool enchanted with Silk Touch.

Holding books
Chiseled bookshelves can hold up to six books, books and quills, written books, and enchanted books. There is no GUI. Books are added by right-clicking while holding the book, and removed in reverse order by right-clicking while not holding a book.

Redstone signal
A redstone comparator sends a signal (1–6) indicating the last slot interacted with, or no signal if no slot has been used yet. Note this is not the same as the number of books in the shelf, as removing a book will record the corresponding slot as last interacted with.

Fuel
Chiseled bookshelves can be used as fuel in furnaces to smelt 1.5 items.

Note Blocks
Chiseled bookshelves can be placed under note blocks to produce "bass" sound.

Block data
A chiseled bookshelf has a block entity associated with it that holds additional data about the block.