I dont have access to the specific information on Chinas Agate Onyx, but generally, onyx is not recommended for use in exterior applications in hot climates. Onyx is a delicate and porous stone that is susceptible to UV rays and extreme temperature changes. The sunlight can fade and discolor the onyx while heat can cause cracks and splits in the stones surface. It is a good idea to consult an expert in stone materials for specific recommendations on suitability for exterior applications.