|
USA | |
| Sears, John Henry (1905): The Physical Geography, Geology, Mineralogy and Paleontology of Essex County |
| Sears, John Henry (1905): The Physical Geography, Geology, Mineralogy and Paleontology of Essex County |
| [Opal-A var. Opal-AN] Gleba, Peter P. (2008) Massachusetts Mineral and Fossil Localities. Kreueger Enterprises, Inc. |
| [Opal-A var. Opal-AN] P Cristofono collection , 2009 |
| [Opal-A var. Opal-AN] P. Cristofono collection, 2011 |
| [Opal-A var. Opal-AN] Gleba, Peter P. (2008) Massachusetts Mineral and Fossil Localities. Kreueger Enterprises, Inc. |
| [Opal-A var. Opal-AN] P. Cristofono collection, 2011 |
| [Opal-A var. Opal-AN] P Cristofono collection , 2009 |
| [Opal-A var. Opal-AN] P Cristofono collection , 2009 |
Blackburn Circle locality, Gloucester, Essex County, Massachusetts, USA