Emerald Tablet

Emerald Tablets are small green items found typically near Orbs of True Knowledge, primarily significant for the game lore they contain. When examined, tablets will at first show their text in glowing green glyphs, which slowly morphs into readable text. Every tablet is different, and most are accompanied by an Orb of True Knowledge, with the exception of the Secretorum Hermetis and Tabula Smaragdina.

Uses
Emerald Tablets can be used as weapons by throwing them at enemies, similar to rocks created by the Summon Rock spell. This can be highly effective against most enemies, as they do considerable damage and are counted as accidental ('trick') kills, rewarding twice as much gold dropped. Physics damage is highly effective even against powerful enemies such as Stevari, so having a tablet on hand can provide a powerful if sometimes unwieldy weapon.

They can also be converted into gold when placed on the altar on top of the floating island above the Mountain, although converting too many can trigger Hell Gazers to spawn. See the Forest page for details.

Stone Tablets
When placed on the Anvil at the bottom right of the Hiisi Base, certain tablets can be "reforged" into Stone Tablets. The name of the tablet remains the same, but the text content changes. Most numbered tablets can be converted in this manner, and the resulting stone tablet will contain a hint at which materials are required to reveal hidden glyphs in the Orb Room the tablet came from. Adding the material(s) to one of the basins in the orb room (after removing the water they usually contain) will reveal glyphs which can be translated into Finnish, revealing some of the story of the game.

Trivia

 * The Emerald Tablets and many of the quotes on them are references to the real Emerald Tablet, which is occasionally referenced in Occult, Alchemical and esoteric contexts.
 * Emerald Tablet Volume V contains a quote from Monty Python and the Holy Grail, fitting the Holy Bomb spell next to it.