If by Olivine you mean "olive oil", then Lots of things.
You use fly
the port in olivine city.
The Light house is at Olivine city. First use HM Fly and fly to "Olivine City". When you get there walk down to the bottom right corner of Olivine city and there's the light house.
Olivine fractures.
go up the stairs or use the elevator
Olivine city
Its not at the port
First, travel to Olivine City. Then, surf Southwest of Olivine to get to a Whirlpool. Then, use a Pokemon with Whirlpool to go across the whirlpool to get into the Whirl Islands.
strength is in olivine city in the olivine cafe
you can find olivine rocks in volcanoes in Greenland.
A Fisherman gives it to you in Olivine
the cafe in olivine is to the LEFT of the poke centre,