Need to find those pesky Rakata Energy Cubes? You need four of these to get the Green matrix Shard datacron on Belsavis. Luckily, you only need four for a group, each person doesn't need to have them.
These are the most common and reliable locations. There a few outside The Tomb, but the spawns are rare.
Location A:
Location B:
Location C:
Location D:
Location E:
Location F:
Location G:
Location H: