The best types of wood are white pine and apple. In fact, a large piece of white pine board in a chin's cage can serve a couple of purposes. It can give a chinchilla something to gnaw on as well as a place to sit when a wire bottom cage becomes uncomfortable on the chin's feet. Another nice thing about white pine boards is that they can be found at any lumber store. Certain types of wood are actually poisonous to chinchillas and should be avoided.
Some owners provide their chinchillas with a pumice stone, but wood is probably more common.
There are times when a chinchilla's diet does require special attention, such as when very young, pregnant, nursing, or when recovering from disease or illness. These special situations are beyond the scope of this discussion. You can get additional information about these special situations from your breeder or from books about chinchillas. Water Chinchillas need fresh water. Water should be changed at least every other day.