Where do you get a thunder stone in black 1?

Question

I have some Eevee' s and I want a jolteon so where

Answer 1

Dust clouds, (in caves) Shopping Mall Nine, Chargestone Cave, and Black City.

Source

Answer 2

>Route 9, Chargestone Cave, Wellspring Cave (Dustcloud), Chargestone Cave (Dustcloud), Mistralton Cave(Dustcloud), Twist Mountain (Dustcloud), Challenger's Cave (Dustcloud), Victory Road (Dustcloud), Giant Chasm(Dustcloud)
You can buy it from Black City also
There is a Pikachu Event that got Thunderstone also

Source experience