There are five datacrons on Belsavis. The blue mastery datacron requires some finesse with platforming, the matrix shard requires a special item, while the other three are quite easy to get. They provide moderate attribute bonuses. All five are required for the Belsavis Datacron Master achievement.
The Belsavis +4 blue mastery datacron.
Codex type: Achievement: Datacrons
Codex location: Belsavis : The Tomb
Codex coordinates: -784, -1929
Faction: Both
Class: Bounty Hunter - Imperial Agent - Jedi Consular - Jedi Knight - Sith Inquisitor - Sith Warrior - Smuggler - Trooper
Associated Achievement: Belsavis Datacron Master
The Belsavis +4 green endurance datacron.
Codex type: Achievement: Datacrons
Codex location: Belsavis : High Security Section, Lost Caver
Codex coordinates: -993, -449
Faction: Both
Class: Bounty Hunter - Imperial Agent - Jedi Consular - Jedi Knight - Sith Inquisitor - Sith Warrior - Smuggler - Trooper
Associated Achievement: Belsavis Datacron Master
The Belsavis +4 yellow presence datacron.
Codex type: Achievement: Datacrons
Codex location: Belsavis : Maximum Security Section
Codex coordinates: -1915, -477
Faction: Both
Class: Bounty Hunter - Imperial Agent - Jedi Consular - Jedi Knight - Sith Inquisitor - Sith Warrior - Smuggler - Trooper
Associated Achievement: Belsavis Datacron Master
The Belsavis green matrix shard datacron.
Codex type: Achievement: Datacrons
Codex location: Belsavis : The Tomb: Cave-Under-Tree
Codex coordinates: -316, -2172
Faction: Both
Class: Bounty Hunter - Imperial Agent - Jedi Consular - Jedi Knight - Sith Inquisitor - Sith Warrior - Smuggler - Trooper
Associated Achievement: Belsavis Datacron Master
Special Requirements: Requires four Rakata Energy Cubes
Rakata Energy Cube
To power the terminal containing the green matrix shard datacron you must first locate four Rakata Energy Cubes spread throughout The Tomb. A full circuit to check all eight spawn locations takes about 8 minutes, assuming the various aggressive creatures don't get attacked. After clicking a Energy Cube on the ground it will disappear and takes 5 minutes to respawn in a random location. These can be inserted into the Matrix Power Consoles, and once all four are filled the Primary Console may be interacted with and selecting Run Shard Sequence will allow you to empower the datacron for the whole world for a few minutes. Once a character has obtained the corresponding datacron they will no longer be able to collect Rakata Energy Cubes.
Various spawn points of Rakata Energy Cubes.
Item: Rakata Energy Cube
Item location: Belsavis : The Tomb
Item coordinates: Multiple Locations
Faction: Both
Class: Bounty Hunter - Imperial Agent - Jedi Consular - Jedi Knight - Sith Inquisitor - Sith Warrior - Smuggler - Trooper
Associated Achievement: None
The Belsavis +4 purple mastery datacron.
Codex type: Achievement: Datacrons
Codex location: Belsavis : High Security Section
Codex coordinates: -502, 767
Faction: Both
Class: Bounty Hunter - Imperial Agent - Jedi Consular - Jedi Knight - Sith Inquisitor - Sith Warrior - Smuggler - Trooper
Associated Achievement: Belsavis Datacron Master