In the book, the heroine was living in a convent, but then some gods became greedy for power and fought the war which caused Jade to be unleashed on the Earth. So she had to travel with companions to restore balance and take back power from the gods. On her way, she met a boy who can shapeshift but cannot talk because his tongue was missing.
Possibly "The Jade Demons Quartet" by Robert E. Vardeman (comprising Quaking Lands, Frozen Waves, Crystal Clouds and White Fire). From an entry on Scribd.com:
Kesira Minette's world has shattered amid a terrible rain of jade. The magical jade has killed the patron demon of her order and turned ordinary humans into strange werecreatures. Worse, the demons who were not killed have become...insane. She leaves the safety of her cloistered existence, accompanied by a sentient green bird and a tongueless shapeshifter, Molimo.
(Image from above website).