Head to Quicksand Caves through the Western Altepa Desert entrance at (D-12). To get here, go to the far end of the visible map at (C-11)/(D-11), then follow the wall where you will soon enter a hidden tunnel.
Talk to the Goblin Geologist for a short dialog indicating that he has placed markers onto your map.
There are nine green markers on your map spread out across the Quicksand Caves areas.
The markers are under the markers tab in your map view.
There are many ??? spots in the caves. Which ones you have been assigned appear to be random.
The markers will remain on your map until you complete the quest.
The markers will only be available on the PC/console that is used to talk to the Goblin Geologist on. However, the data can be saved to, and then loaded from the server, or copied from the machine to the other.
Explore the area and examine each of the ???s marked on your map.
Based on the fact that these stones cannot be behind the weight sensors you'll only need to check a couple of entrances to the Quicksand Caves, entrances (2)(There is a second map LOCATED AT D-11 and that will take you to another map that also has ??? markers on it See below for ??? locations)& (6) on Western Altepa Desert/Maps will let you check two of the 8 possible maps in Quicksand Caves and the remaining possible stones can be found by going into entrance (1) on Eastern Altepa Desert/Maps.
Map 8: E-6, F-5, G-9, H-7, I-7, I-9, (West @ D-11 on map 3 to reach map 8)
Note: There is a glitch that happens sometimes where one or more of the ???'s won't appear on the map markers making it so you have to search for them without a marker. Talking to the Goblin Geologist again may fix the problem.
Note: When dual boxing this mission, both characters had to find the same nine ??? so it's likely to be dependent on when you accept the mission.
A dire development! Your moogle partner's betrothed, the fair Kupiruru, has been kidnapped by Toto's band of hoodlums! Make haste for the Chamber of Oracles to save the moogle maiden from a frightening fate!