Tilleyite

Source: Wikipedia, the free encyclopedia.
Tilleyite
2V angle
85-89°
Dispersionr < v
References[2]

Tilleyite is a rarely occurring

crystals
and spherical grains. In its pure form it is colorless and transparent, however due to multiple refractions of light from lattice defects or polycrystalline formation, it can also appear white, with the transparency decreasing accordingly.

History

Tilleyite was first described from an occurrence at the Crestmore Quarry in Riverside County, California in 1932 by Esper Larsen and Kingsley Dunham, and named after Cecil Edgar Tilley (1894-1973), a professor of geology at Cambridge University, in recognition of his contributions to the study of metamorphism.[3] Its type material is held at Harvard University, and the National Museum of Natural History.[4]

Crystal Structure

Tilleyite crystallizes monoclinically in the space group P21/a (space group no. 14, position 3) with the lattice parameters a = 15.11 Å; b = 10.24Å; c = 7.58 Å,and β = 105.2°, with 4 formula units per unit cell.[5]

Formation and occurrence

Tilleyite is formed by

minerals include calcite, fluorite, gehlenite, grossular, vesuvianite and wollastonite.[6]

More generally, it occurs at

Carlingford, Ireland, and on the island of Muck, Scotland.[7]

See also

External links

References

  1. doi:10.2138/am.2010.3371
    .
  2. ^ Tilleyite on Mindat.org
  3. ^ Larsen, Esper S.; Dunham, Kingsley C. (Nov 1933). "Tilleyite, a new mineral from the contact zone at Crestmore, California". American Mineralogist. 18 (11): 469–473. Retrieved 6 June 2023.
  4. ^ "Tilleyite" (PDF). Mineral Date Publishing. 2001. Retrieved 6 June 2023.
  5. ISBN 3-510-65188-X
    .
  6. ^ Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2001). "Tilleyite" (PDF). Handbook of Mineralogy, Mineralogical Society of America.
  7. ISBN 1-86239-081-9
    .
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