For this Trophy, Ratchet and Clank most collect all 100 Desert Crystal from the desert area of the Mining Facility on planet Tabora. Desert Crystals are purple crystals that can either be found encrusted in rock (which can be broken with a OmniWrench 10000 or a gun) and from defeating a Desert Dune Monster (which always carry one) whom hide underground under a pile of sticks until you near them. Ratchet and Clank are required to grab 10 for story progression (they are unable to leave Tabora without them), leaving 90 left to collect. Its recommend to have some good weapons for crowd control as Mutant Sandflies and Spitting Dune Crawlers are often guarding a Desert Crystal, and heavy weapons for Desert Dune Monsters. While you can do this task as soon as you reach the Mining Facility on planet Tabora and talk to the Mystic, you can also do this much later in the game after you acquire the Mapper off Allgon Moon from defeating the Mothership after reaching planet Allgon City, planet Damosel. The Mapper shows the exact location of every Desert Crystal within the Mining Facility of Tabora, so you won't potentially be running around in circles. If you choose to forgo the Mapper, use map to keep track of areas in the Mining Facility you've haven't been to yet, which are colored gray. Also helps to have the Visibomb Gun to use as a drone to find Desert Crystals and Desert Dune Monsters.