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|Name:||Named after its discovery locality at the Sea of Tranquillity, the Moon.|
Lunar rock samples brought back from the Moon by the Apollo 11 mission in 1969 were found to contain three minerals that had never been seen on Earth. Terrestrial occurrences for pyroxferroite and armalcolite were discovered in the next few years, but until 2011, tranquillityite was only known from returned moon rock samples and from lunar and martian meteorites. However, the mineral has now been discovered as an uncommon accessory phase in terrestrial mafic rocks, at six localities in Western Australia. [http://geology.gsapubs.org/content/40/1/83.abstract]
Classification of Tranquillityite
|IMA status:||Approved 1971|
|Strunz 8th edition ID:||8/B.07-10|
|Nickel-Strunz 10th (pending) edition ID:||9.AG.90|
9 : SILICATES (Germanates)
A : Nesosilicates
G : Nesosilicates with additional anions; cations in >  +-  coordination
|Dana 8th edition ID:||220.127.116.11|
78 : Unclassified Silicates
|Hey's CIM Ref.:||14.10.33|
14 : Silicates not Containing Aluminum
10 : Silicates of Zr or Hf
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Type Occurrence of Tranquillityite
|Type Locality:||Mare Tranquillitatis (Sea of Tranquility), The Moon|
|Year of Discovery:||1971|
Physical Properties of Tranquillityite
Crystallography of Tranquillityite
|Cell Parameters:||a = 11.69Å, c = 22.25Å|
|Ratio:||a:c = 1 : 1.903|
|Unit Cell Volume:||V 2,633.24 Å³ (Calculated from Unit Cell)|
Optical Data of Tranquillityite
|RI values:||nα = 2.120|
|Maximum Birefringence:||δ = 2.120|
Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
|Dispersion:||r < v|
Chemical Properties of Tranquillityite
|Essential elements:||Fe, O, Si, Ti, Zr|
|All elements listed in formula:||Ca, Fe, O, Si, Ti, Y, Zr|
Relationship of Tranquillityite to other Species
|Related Minerals - Nickel-Strunz Grouping):|
|Related Minerals - Hey's Index Grouping:|
Other Names for Tranquillityite
|Health Warning:||No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.|
References for Tranquillityite
Proceedings of the 2nd Lunar Scientific Conference (1971): 1: 39-45.
American Mineralogist (1973): 58: 140-141.
Proceedings of the 8th. Lunar Scientific Conference (1977): 2: 1831.
Rasmussen, B. et al (2012) Tranquillityite: the last lunar mineral comes down to Earth. Geology, 40(1) 83-86.
Internet Links for Tranquillityite
Localities for Tranquillityite
The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
(TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
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