Opal-AN from Providence County, Rhode Island, USA
USA | |
| Miller, 1971. RI Minerals & Their Locations |
| Gems & Minerals 395 (August, 1970). |
Eckert, Allan W. (1997): The World of Opals, p. 346. | |
| George, Gilbert (1972). Latest Finds at Rhode Island Road Cuts(Micromounters of New England no. 17, Feb. 1972). |