In DragonVale for the Android and iOS Systems (iPhone and iPad, etc.), the Silver Dragon is Treasure Dragon similar to the Gold Dragon, Platinum Dragon, and Bronze Dragon.
The Silver Dragon has a base breeding time of 47 hours, sells for 4,000,000 coins, and earns 500,000 XP for successful breeding once you reach level 17.
To breed the Silver Dragon, you must mix dragons Cold and Metal elements. Metal + Cold or Metal + Evergreen are popular combinations. If you get a 47 hour incubation time then you’ve got it.
Check out my DragonVale Breeding Guide for more dragon breeding combinations.