The light crystal is one of the four crystals hidden throughout the environment as of Alpha 0.0.82. It is also known as the Protection crystal. It is a bright yellow in color, and it's vibrance is greater than the other crystals.
The light crystal is located on an altar similar in appearance to a sword plinth such as in the video game The Legend of Zelda or King Arthur's fables. This Altar of Protection is located north-east of the Blacksmith's Shop, along the northern border of the map. In the image below, you can barely see the shop behind the three large trees on the right.
Touching the CrystalEdit
Nearing the crystal, it's labeled as Crystal (Unknown) until you pick it up, similar to the dark crystal. Once you do pick it up, the Protection effect emanates from the crystal in a large radius while held. After dropping the crystal, it is now labeled as Light Crystal (Protection) and ceases to emit it's Protection effect.