After many researches, i found this rock! A retailer, tropical fish specialist near from Montreal (Quebec, Canada) located in Laval have this rock called "dragon rock", used by Takashi Amano. This rock is taken from a chinese mountain. I send an order by e-mail and bought few pieces. Great! The same as the picture...
i think they are the only one to sell theses rock in Canada.
Oups..i forgot, the store is AquaPassion.
(here the link : www.aquapassion.com
I hope it will help you.