Are chalk pastels similar to solid oil pastels or to a colored chalk? Seems like one day I ask a bookstore for chalk pastels and seems like they didn't know it. They just shown me these solid oil pastels. Just asking if they're similar or not. If not, can colored chalk be enough as a substitute for weathering?

The Oil kind will NOT work for weathing as normal techniques go.
They are (in the US) refered to as Pastels in general then labeled on the box as Oil or Chalk.
You want the chalk ones.

Be careful about buying Colored Chalk sometimes that is geared to kids for art projects in school and such and aren't as nice in quality as artist chalk pastels.

What Slodder said. If in doubt, run you finger along the chalk. If you get a dusty residue, you've got the right ones.

Hi Shonen

Don't look for the pastels in a bookshop... go to an Artist supplies store. You'll find a much wider range. :-)

Cheap chalks are really coarse and gritty , spend a little extra and get artist's chalk pastels... it's worth it in the long run.

All the best

Rowan