He's right, it ain't.
3 seconds sound clip from the The Shawshank Redemption movie soundboard.
You can hear this line at 00:46:56 in the Blu-ray version of the movie.
Quote context
[...]
- I figure we owe him that much for the beer.
- The man likes to play chess. Let's get him some rocks.
- Guys? I got one! I got one. Look.
- That isn't soapstone! And it ain't alabaster, either.
- What are you, a fucking geologist?
- Well, what the hell is it then?
- No, horse shit. Petrified. (Horse whinnies)
[...]