Opal from Mohave County, Arizona, USA
USA | |
| Granger, H.C. & Raup, R.B. (1962), USGS Bull. 1147A, Recon. Study of Uranium Deps. in AZ: A16-A18. |
| Mouat, M. M. (1962) Manganese oxides from the Artillery Mountains area, Arizona. American Mineralogist, 47 (5-6) 744-757 |
[Opal-A var. Opal-AN] Galbraith, F.W. & Brennan (1959), Minerals of AZ: 87. | |
| Galbraith, F.W. & Brennan (1959), Minerals of AZ: 87. |
| Theodore, T.G., et al (1987), USGS PP 1361: 148-149 (Table 11). |