This quest is gained in Vault 19. You can recieve it from Philip Lem or Samuel Cooke, and the quest changes slightly depending on who you get it from.
Philip will request that you cut off access to the caves. Go into the caves, and take the right path. Here you will find the Microcline Rock. You will be given two options: blowing up the mines (requires 3 C4) or blowing up the mines and the vault (requires 5 C4, and fails the quest). You can find 4 packs of C4 in the vault:
- Behind the front desk, by the filing cabinets.
- In the cafeteria by two vending machines.
- Near the Overseer's office, near the door with the firehose box.
- Under a couch in the Blue Sector living quarters.
After blowing up the caves, return to Philip. He will want to surrender to the NCR, but you can convince him to side with the Great Khans with 40 speech. He will ask you to speak to Papa Khan at Red Rock Canyon, and once you have, speaking to him again will finish the quest.
Samuel will ask that you clear the fire geckos out from the caves. There aren't that many to deal with, and once killed, returning to Samuel will get you 300 caps. He will then send you to speak to Papa Khan, at Red Rock Canyon, to create an alliance. Talking to Papa Khan and then returning to Samuel will finish the quest.