My Salvage group did Silver Sea Remnants today, we obtained 4 Alexandrite (Screenshot not available).
The path we took:
Hammerblow
Powderkeg
GGears
CC
With TH4, we dropped 3 killing the gears in the GGears room (none from Rampart), and 1 dropped from killing the Gear Train on the CC floor.
Would be cool to see what other people's experiences are, and possibly workout what sort of drop rate we're looking at, someone in my Salvage group suggested the drop rate is similar to Card drop rates.
(Please move to another forum if necessary).