Gabrielle Chanel originally used a special tweed fabric, but it seems that by now, it needs its own term ("tweed" just doesn't do it justice). (photo from Fairycart: How Chanel's tweed jacket was born and my fairies)
McGINN also has a fantastic Chanel-look-alike boucle jacket this season (designed exclusively for Nordstrom's Via C Designer Dept.with faux pearls, leather-intertwined chain and all -- the McGINN "ELIZABETH" Boucle Jacket.
The four key features of a Chanel-style jacket. This article explains Susan Khalje's method of creating a muslin pattern for fitting, quilting the silk lining to the tweed fabric, and completing most of the jacket by hand.