From HandWiki
CategoryZircon group
(repeating unit)
Strunz classification9.AD.45
Crystal systemTetragonal
Crystal classDipyramidal (4/m)
H-M symbol: (4/m)
Space groupI41/a
Unit cella = 4.738, c = 10.506 [Å], Z = 4
Formula mass183.31 g/mol
ColorColorless to white
Crystal habitEpitaxial - crystallographic alignment with a precursor mineral, occurs as inclusions in other minerals.
Mohs scale hardness7.5
Specific gravity5.16
Optical propertiesUniaxial (+)
Refractive indexnω=1.64, nε=1.655

Reidite is a very rare mineral created when zircon undergoes high pressure and temperatures. It is commonly associated with meteorite impacts.

On Earth, reidite has been found only in eight crater impacts: the Chesapeake Bay Crater in Virginia; Ries Crater in Germany ; Xiuyan Crater in China ; Woodleigh Crater in Western Australia;[3] Rock Elm Crater in Wisconsin;[4] and Dhala Crater in India ,[5] Pantasma crater in Nicaragua and Lake Mien in Tingsryd Sweden, impact 120 M years ago,

In 2015 an occurrence of reidite was reported from the Precambrian Stac Fada Member structure in North West Scotland, further supporting its impact origin.[6]

Libyan desert glass may show lattice deformation in zircon that is interpreted as evidence of this material having previously contained reidite, and as such constitutes strong evidence for its impact origin.[7]

Name origin

Reidite is named after the scientist who first created the high pressure phase in the laboratory in 1969, Alan F. Reid.


Zircon morphs into reidite when shock waves from meteorite impacts hike up pressures and temperatures to extreme levels, equal to those deep inside the Earth where diamonds form. The pressure makes minerals tightly repack their molecules into denser crystal structures. Reidite has the same composition as regular zircon but is about 10 percent denser.[4]

Related silica minerals

Relationship of Reidite to Other Specimens
9.AD.25 Uvarovite Ca3Cr2(SiO4)3
9.AD.25 Wadalite (Ca,Mg)6(Al,Fe3+)4((Si,Al)O4)3O4Cl3
9.AD.25 Holtstamite Ca3(Al,Mn3+)2(SiO4)2(OH)4
9.AD.25 Kerimasite Ca3Zr2(SiO4)(Fe3+O4)2
9.AD.25 Toturite Ca3Sn2(SiO4)(Fe3+O4)2
9.AD.25 Momoiite (Mn2+,Ca)3V23+(SiO4)3
9.AD.25 Eltyubyuite Ca12Fe103+Si4O32Cl6
9.AD.25 Hutcheonite Ca3Ti2(SiAl2)O12
9.AD.30 Coffinite (U4+,Th)(SiO4)1-x(OH)4x
9.AD.30 Hafnon HfSiO4
9.AD.30 Thorite (Th,U)SiO4
9.AD.30 Zircon ZrSiO4
9.AD.30 Stetindite Ce4+SiO4
9.AD.35 Huttonite ThSiO4
9.AD.35 Tombarthite-(Y) Y4(Si,H4)4O12−x(OH)4+2x
9.AD.40 Eulytine Bi4(SiO4)3

See also


  1. "Reidite". Hudson Institute of Mineralogy. Retrieved 18 March 2015. 
  2. "Reidite Mineral Data". Retrieved 18 March 2015. 
  3. Discovery of reidite, one of the rarest minerals on Earth, may reveal Australia's biggest crater ABC News, 16 October 2018. Retrieved 17 October 2018.
  4. 4.0 4.1 Oskin, Becky. "Rare Mineral Discovered in Ancient Meteorite Impact Crater". Livescience. Retrieved 24 March 2015. 
  5. Li, Shan-Shan; Keerthy, S.; Santosh, M.; Singh, S.P.; Deering, C.D.; Satyanarayanan, M.; Praveen, M.N.; Aneeshkumar, V. et al. (February 2018). "Anatomy of impactites and shocked zircon grains from Dhala reveals Paleoproterozoic meteorite impact in the Archean basement rocks of Central India". Gondwana Research 54: 81–101. doi:10.1016/ Bibcode2018GondR..54...81L. 
  6. Reddy, S. M., et al. "Precambrian reidite discovered in shocked zircon from the Stac Fada impactite, Scotland." Geology (2015): G37066-1.
  7. Cavosie, Aaron J.. "How we solved the mystery of Libyan desert glass" (in en). 

External links