Philosopher's Stone

The Philosopher's Stone has several features and is the base at which an Aspiring Alchemist starts. Many young Alchemists think that creating the Philosopher's Stone is the culmination of the Art of Alchemy. How wrong they are. It is just the beginning, opening the door to the Transmutation Tablet, dark/red matter and many other things.

Philosopher's Stones are instrumental in the creation of Nova Catalysts, one of the most notable explosive items in Tekkit.

Recipe
stone

stone

Realtime Transmutation
The Philospher's Stone not only gives you the power to change a handful of items into others, but it can also transform the very environment around you! Right Clicking will transmute certain blocks to others, Shift + Right Click will change a block as well (They change back to their previous form if you click again):

This effect costs no Fuel. Transmuting large areas at once can incur a cooldown on the effect.

Pressing "R" will fire a Projectile outwards, if it hits a mob it will transform them into another random mob of that disposition, Peaceful or Aggressive. This effect costs 1 fuel (glowstone dust, redstone dust, e.t.c). Mobs added by other mods will turn into a slime or sheep randomly regardless of that mobs disposition.

Pressing "C" will open a Crafting Table. Be forewarned due to some changes by Mojang, there is a bug making the philosopher stone will jump out of your table into your inventory or worse, it will disappear.

For anyone who previously noticed this mention pressing 'X' for enchanting, this is actually a function of NEI (giving the correct credit) and if on SMP requires OP and cheat mode or on SSP just cheat mode.