- Sulphur Creek District (Sulfur Creek District; Wilbur Springs District)
- Clear Lake Highlands area
| Hanks, Henry Garber (1886), Sixth report of the State Mineralogist: California Mining Bureau. Report 6 part 1, 145 pp.: 125; Anderson, Charles A. (1936), Volcanic history of the Clear Lake area, California: Geological Society of America Bulletin: 47: 635; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 314. |