Opal-C

SiO2·nH2O
Variety of
Opal
OpalSiO2 · nH2O

Where it forms, where it's found

10recorded occurrences
Source · OpenStreetMap

Group, growth & confusion

In the same group
13 members

Literature, links & citation

Citations
  1. 1971Jones, J. B., Segnit, E. R. (1971) The nature of opal I. nomenclature and constituent phases. Journal of the Geological Society of Australia, 18 (1) 57-68 doi:10.1080/00167617108728743DOI: 10.1080/00167617108728743
  2. 1985Graetsch, H., Flörke, O. W., Miehe, G. (1985) The nature of water in chalcedony and opal-C from brazilian agate geodes. Physics and Chemistry of Minerals, 12 (5). 300-306 doi:10.1007/bf00310343DOI: 10.1007/bf00310343
  3. 1994Graetsch, H. (1994) Structural characteristics of opaline and microcrystalline silica minerals. in: Heaney, P.J., Gibbs, G.V., editors. Reviews in Mineralogy Volume 29 Silica - Physical behaviour, geochemistry and materials applications. Mineralogical Society of America, 209-232.
  4. 1994Elzea, J.M., Odom, I.E., Miles, W.J. (1994) Distinguishing well ordered opal-CT and opal-C from high temperature cristobalite by x-ray diffraction. Analytica Chimica Acta, 286 (1). 107-116 doi:10.1016/0003-2670(94)80182-7DOI: 10.1016/0003-2670(94)80182-7
Cite this entry
@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Opal-C — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/opal-c-32186},
  note      = {Accessed 2026-05-11}
}