Opal from selected localities.
USA | |
| [Opal-A var: Opal-AN] Rocks & Min.:8:61-65. |
| [Opal-A var: Opal-AN] The Minerals of New York City & Its Environs, New York Mineralogical Club Bull. Vol. 3, No. 1, Manchester, J.G. (1931): 87. |
| [Opal-A var: Opal-AN] Rocks & Min.: 7:91; 8:38. |
| [Opal-A var: Opal-AN] Rocks & Min.: 8:40. |
[Opal-A var: Opal-AN] Rocks & Min.:7:148 & 8:40. |