Hi there, Liz
Did you talk to Duane about music, Miguel,the truck, the truck again, and then Miguel again?
After you go up to the Mine Co. you need to get Conchita to call you "chico." Talk to her about Obier, the detonator and the rolled-up chart. Did you do that? You need to go out and talk to Nico, the General, Renaldo, and Pearl. Then talk to Conchita at the Mine Co. again before you are set to get the detonator.
If you need more there's a SPOILER FOLLOWING!:
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Here is the more detailed outline of the above:
Go talk to Nico first about the rolled up chart and talk her into distracting the General. Then go to the police station and talk to the General about Nico. When they go out, talk to Renaldo two times about the pyramid. Go out of the police station and talk to Pearl about the pyramid. The police station should be empty now...go in and get a good look around. Then go back to the Mine Co. and talk to Conchita about the chart. Only then can you get the detonator.