Silver Batal (#2) Race for the Dragon Heartstone by Halbrook
Silver Batal and her beloved water dragon Hiyyan have narrowly escaped the greedy clutches of Queen Imea. But while on the run they face new dangers and Hiyyan suffers an injury at the hands of a deadly screw-claw.
With the queen's trackers hot on their tails, Silver, Hiyyan, and their friends learn of a mythical dragon heartstone that could heal Hiyyan. As Hiyyan grows weaker, Silver encounters blinding snowstorms, perilous icy treks, and ferocious ice dragons in a race against time to save her best friend.