Magnetite

Magnetite is a block in Lunacraft which is the most common of the materials assigned a value greater than 0.0 kC (with the possible exception of the Xenobiologicals).

General Information
Magnetites only use is in the production of Magnets. One Magnet is required to Assemble each Slugpistol and one Slugpistol is required for each Turret. You will probably end up with far more Magnetite than you will use, if you collect all the Magnetite you come accross while exploring, unless you are planning on Assembling an army of Turrets.

In Creative mode, Magnetite is not one of the Material blocks that are given to you in your inventory. You will need to explore your moon to find some, look in Water where it is easier to spot. When you do collect some Magnetite you may still find that you cannot Assemble a Magnet.

Infinite Stacks
In Update 1.7.0 the Assembler has a hard time dealing with infinite stacks. Your Magnetite stack will become infinite if you collect 2 blocks, but the Assembler will only treat it as 2 blocks. You can either collect 2 more blocks or use multi-touch to put 4 blocks into the Assembler and then stack those blocks together.

Technically in Creative mode you do not need a Slugpistol for protection, but if you want a higher level Slugpistol, to get rid of Mobs quicker, you will need a Magnet. If you make 2 Magnets, and drag them to the same inventory slot, you will have an infinite stack of Magnets.