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USA | |
| Mustoe, G. E. (1996): Hisingerite—a rare iron mineral from Walker Valley, Skagit County, Washington. Washington Geology 24 (4), 14-19. [https://www.researchgate.net/publication/266138607_Hisingerite_-_a_rare_iron_mineral_from_Walker_Valley_Skagit_County_Washington] |
| Cannon, Bart (1975) Minerals of Washington. Cordilleran, Mercer Island, WA. |
- Springdale Mining District
| Nash, J. T., & Lehrman, N. J. (1975). Geology of the Midnite uranium mine, Stevens County, Washington a preliminary report (No. 75-402). US Geological Survey],. |
Walker Valley, Skagit County, Washington, USA