Add Geologist Lv.1 before you depart to The Guiding Lands
I'm not sure if it's a bug or not, but anyway. Geologist Lv.1 allows you to gather monster material one more time in The Guiding Lands. Obtained materials will be doubled if you have Geologist skill. This is the most important tip for The Guiding Lands. Don't forget to add Geology Jewel!