Reidite

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

Reidite
General
CategoryZircon group
Formula
(repeating unit)		ZrSiO4
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
Identification
Formula mass183.31 g/mol
ColorColorless to white
Crystal habitEpitaxial - crystallographic alignment with a precursor mineral, occurs as inclusions in other minerals.
CleavageNone
FractureIrregular/uneven
TenacityBrittle
Mohs scale hardness7.5
LusterAdamantine
StreakWhite
DiaphaneityTranslucent
Specific gravity5.16
Optical propertiesUniaxial (+)
Refractive indexnω=1.64, nε=1.655
Birefringence0.0150
PleochroismNone
References[1][2]

On Earth, reidite has been found only in seven 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] and Pantasma crater in Nicaragua.

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.

Formation

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]

Relationship of Reidite to Other Specimens
9.AD.25UvaroviteCa3Cr2(SiO4)3
9.AD.25Wadalite(Ca,Mg)6(Al,Fe3+)4((Si,Al)O4)3O4Cl3
9.AD.25HoltstamiteCa3(Al,Mn3+)2(SiO4)2(OH)4
9.AD.25KerimasiteCa3Zr2(SiO4)(Fe3+O4)2
9.AD.25ToturiteCa3Sn2(SiO4)(Fe3+O4)2
9.AD.25Momoiite(Mn2+,Ca)3V23+(SiO4)3
9.AD.25EltyubyuiteCa12Fe103+Si4O32Cl6
9.AD.25HutcheoniteCa3Ti2(SiAl2)O12
9.AD.30Coffinite(U4+,Th)(SiO4)1-x(OH)4x
9.AD.30HafnonHfSiO4
9.AD.30Thorite(Th,U)SiO4
9.AD.30ZirconZrSiO4
9.AD.30StetinditeCe4+SiO4
9.AD.35HuttoniteThSiO4
9.AD.35Tombarthite-(Y)Y4(Si,H4)4O12−x(OH)4+2x
9.AD.40EulytineBi4(SiO4)3

See also

References
  1. "Reidite". mindat.org. Hudson Institute of Mineralogy. Retrieved 18 March 2015.
  2. "Reidite Mineral Data". Webmineral.com. 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. Oskin, Becky. "Rare Mineral Discovered in Ancient Meteorite Impact Crater". Livescience.com. 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.; Indu, G.K. (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. Bibcode:2018GondR..54...81L. doi:10.1016/j.gr.2017.10.006.
  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". The Conversation. Retrieved 2019-10-12.
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