Opal from selected localities.
USA | |
| Browne, J.R. (1869), Report of J. Ross Browne on the mineral resources of the states and territories west of the Rocky Mountains (US Treasury Dept.), 674 pp., H.H. Bancroft and Co., San Francisco [reprint of 2]: 56; Kunz, George Frederick (1905a), Gems, jewelers’ materials, and ornamental stones of California: California Division Mines Bulletin 37, 171 pp.: 76; Lewis, W. Scott (1933), Occurrences of opal in California: Rocks & Minerals: 8: 36-37. |
Clark, William B. & Lydon, Philip A., California division of mines and geolgy (1963) MINES AND MINERAL RESOURCES OF CALAVERAS COUNTY, CALIFORNIA, county report number 2, pages 87-88. | |
Clark, William B. & Lydon, Philip A., California division of mines and geology (1963) MINES AND MINERAL RESOURCES OF CALAVERAS COUNTY, CALIFORNIA, county report number 2, page 91 | |
USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10109141. |