Possible Clues:

• Stone cottage in Brittany occupied by artist (northern)
• Stone: garnet I fancy
• Carelessly train, for example, with something so heavy.
• Rock hurtled into French cottage
• Building material rating revised by English
• Plymouth Rock, essentially
• Rock: one pocketed in fake garnet
• Stone from six counties placed in jar
• Rock that's an anagram of "tearing"
• Rock inverted in filling fireplace