Welcome to this guide!
So, you want to know how to find portal peices? You have come to the right place!

This guide focuses on Terra (Starting planet), but some things discussed may apply to other planets.

THIS GUIDE DOES NOT WORK ON MULTIPLAYER WORLDS!

First things first, where do you find them?

They are quite deep into the ground. Dig untill you can start to see lava.
Once you reach that level, dig around a little bit, and you should see something.

Surprisngly your map can see much farther than you can.
Dig around a little bit, then open your map with the "M" key.

What you are looking for is a teal/blue glow.

Good job! You found the portal chest, not the peice.

Dig over to the portal peice and use a hammer to break the chest.

WARNING! Only attempt to break the chest if you have a IRON hammer or better! Use of any other hammer will DESTROY THE CHEST WITHOUT DROPING A PEICE!

Yes! On Terra (starting planet), there are two different chests, Yellow ones and green ones.

The yellow ones lead to Seth (desert planet) and the green lead to Umbra (halloween planet).

This is a image of a Seth chest. If you can tell, the little corners of the chest are a yellow color. It is hard to tell the color of the chests because of their slight blue glow, but without that glow it would be very hard to find them.

For a portal to work, you require THREE portal peices of the same type. Ex: To go to Seth, you require 3 Seth portal peices.

There are about 11 planets in-game right now.
The fine gentelmen over at the pixlbits forums for Junk Jack made a nice portal map.
Visit them right here![wiki.pixbits.com]
Map:

Edit: There is now 12 planets, i don't know what the new one is :P

Edit 2: The newest planet added is "Tor". The portal peices can be found on "Mykon".
Thanks to user [Spook] for this info!

Edit 3: Apparently the Devs have done some shifting around with the planet peices, so
take the shown picture as more of a rough guide than a real map.

Now that you know how to get portal peices, go out and get them!
It may be hard, but exploring cool planets is worth it!
Have fun and thanks for reading!










Images are from the pixlbit forums (Click me for link[wiki.pixbits.com]) and personal game play.