Mythril Mine
Item:
Ether, Tent, "Long Range" Materia, Mind Source, Elixir, Hi-Potion
After crossing the marsh, you'll encounter a Midgar Zolom that has been impaled on a broken tree. Only Sephiroth could have through of such a gruesome act, so you must be on the right track. The Mythril Mine is just ahead.
The mine itself is fairly small, so it's quite difficult to get lost in. There are plenty of items to pick up.
Tips:
Before exiting the mine, the team runs into Rude, Elena, and Tseng of the Turks. It appears the Turks are also pursuing Sephiroth. Elena, the newest Turk, slips up and mentions that Sephiroth is headed for Junon Harbor, which isn't far from the mine.
If you follow Tseng out of the mine, you'll see a large condor on the nearby hill. You've come across Fort Condor, home of a small band rebels fighting against Shinra. Take the opportunity to stop by and get some rest before moving on the Junon Harbor.