What is the name of Tolkien’s unfinished mythology first published posthumously in 1977?

The Silmarillion is Tolkien’s unfinished mythology, published posthumously in 1977.

The book was edited and arranged by Christopher Tolkien after J.R.R. Tolkien’s death. It presents stories from the creation of the world through the First Age and includes the Ainulindalë, the Valaquenta, the Quenta Silmarillion, the Akallabêth, and the closing Of the Rings of Power and the Third Age.

Its central First-Age narrative concerns the Silmarils, three jewels made by Fëanor. Their theft by Morgoth drives many of the book’s wars, oaths, journeys, and tragedies. The work also contains major accounts of Elves, Men, Valar, Beleriand, and Númenor.

The Silmarillion was not a completed manuscript prepared for publication by Tolkien himself. Christopher Tolkien selected and reconciled material from many drafts, which explains differences in style and continuity. The Book of Lost Tales is an earlier phase of Tolkien’s mythology, not the 1977 published volume.