The Hillman Hall of Minerals and Gems is a notable mineral and gem collection within the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania. Comprising over 1,300 specimens, Hillman Hall has gained a reputation as one of the finest mineral exhibitions in the United States. The museum's first mineralogy exhibit consisted of about 550 specimens loaned by Professor Gustave Guttenberg, then purchased after his death in 1896 to become the core of the museum's collection. In subsequent decades, it was augmented primarily by gifts, including Andrew Carnegie's 1904 donation of the notable mineral collection of William W. Jefferis of West Chester, Pennsylvania.