Find shard in Mountain Temple was a mission in Jak II. Jak was looking for answers regarding the Tomb of Mar, for which in turn Onin send Jak to collect three artifacts from the Mountain Temple, one of them was the Shard.
The PlayStation 3 and Vita versions of this mission are related to a trophy named "Just the Artifacts Ma'am", completing this one and the other two related artifact missions at the Mountain Temple will reward you with a bronze trophy.
A collection of three mission spread out over a single large area, each with its own linear path. When entering the mountain area and taking the elevator down and head forward (encountering some manic heads) to meet the new hopper anyway, a rather weak metal head. For the shard, take a right and go through this pass to encounter a huge re-spawning swarm of hoppers. Punch through with the Scatter Gun to encounter a centurion (double the health compared to before).
After the centurion and a couple of jumps you come across a big dark eco lake with several precursor metal cubes spread out over it. The goal here is to hit the cubes to create a path to the next and so forth. If you screw up you'll have to press the button at the start at the first cube to reset them. After this puzzle you'll just need to climb to the large precursor plateau here and fight the ram head.
A sub-boss of sorts guards the shard artifact, it acts much like the typical rhino or bull enemy and its only attack is to charge you. Dodge it by punching or rolling sideways and then turn around to shoot its weak underbelly (as it stands up on its hind legs) with the Blaster's punch plus fire combo. It is otherwise invulnerable to your attacks. After killing it you can pick up the Shard from the temple nearby and jump back down from the platform to the starting area.