The Grenville Province, covering much of upstate New York, southeastern Ontario, and southern Québec, has been the source of many amazing mineral specimens. Its crystalline rocks are more than a billion years old, and unlike most mineralogical heritage sites, new discoveries are the rule rather than the exception.The province also contains deposits of commercially important minerals such as iron, zinc, talc, garnet, apatite, and mica. More than 400 photographs highlight specimens from the world-renowned collections of the Canadian Museum of Nature, the New York State Museum, and selected private collections. This pleasurable journey includes sections devoted to colorful gemstones and fluorescent minerals, and explains the mineralogical, geological, and historical significance of these minerals.