Reidite

Reidite
General
Category	Zircon group
Formula (repeating unit)	ZrSiO4
Strunz classification	9.AD.45
Crystal system	Tetragonal
Unit cell	a = 4.738, c = 10.506 [Å], Z = 4
Identification
Formula mass	183.31 g
Color	Colorless to white
Crystal habit	Epitaxial - crystallographic alignment with a precursor mineral, occurs as inclusions in other minerals.
Crystal symmetry	Tetragonal - dipyramidal H-M symbol (4/m) Space group: I 41/a
Cleavage	None
Fracture	Irregular/uneven
Tenacity	Brittle
Mohs scale hardness	7.5
Luster	Adamantine
Streak	White
Diaphaneity	Translucent
Specific gravity	5.16
Optical properties	Uniaxial (+)
Refractive index	nω=1.64, nε=1.655
Birefringence	0.0150
Pleochroism	None
References	[1][2]

Reidite is a rare mineral that has been found only in four crater impacts: the Chesapeake Bay Crater in Virginia, Ries Crater in Germany, Xiuyan Crater in China, and Rock Elm Crater in Wisconsin in the United States.^[3]

In 2015 an occurrence of reidite was reported from the Precambrian Stac Fada Member structure in North West Scotland, confirming its impact origin.^[4]

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.^[3]

Related silica minerals

Relationship of Reidite to Other Specimen

9.AD.25	Uvarovite	Ca3Cr2(SiO4)3
9.AD.25	Wadalite	(Ca,Mg)6(Al,Fe^3+)4((Si,Al)O4)3O4Cl3
9.AD.25	Holtstamite	Ca3(Al,Mn^3+)2(SiO4)2(OH)4
9.AD.25	Kerimasite	Ca3Zr2(SiO4)(Fe^3+O4)2
9.AD.25	Toturite	Ca3Sn2(SiO4)(Fe^3+O4)2
9.AD.25	Momoiite	(Mn^2+,Ca)3V2^3+(SiO4)3
9.AD.25	Eltyubyuite	Ca12Fe10^3+Si4O32Cl6
9.AD.25	Hutcheonite	Ca3Ti2(SiAl2)O12
9.AD.30	Coffinite	(U^4+,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	Ce^4+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

• Rock Elm Disturbance
• List of minerals

References

1. "Reidite". mindat.org. Hudson Institute of Mineralogy. Retrieved 18 March 2015.
2. "Reidite Mineral Data". Webmineral.com. Retrieved 18 March 2015.
3. Oskin, Becky. "Rare Mineral Discovered in Ancient Meteorite Impact Crater". Livescience.com. Livescience. Retrieved 24 March 2015.
4. Reddy, S. M., et al. "Precambrian reidite discovered in shocked zircon from the Stac Fada impactite, Scotland." Geology (2015): G37066-1.

External links

• List of Minerals