ACASTA GNEISS
 
 
 
Acasta Gneiss
Metaplutonic
Orthogneiss (Metamorphosed granite)
Hadean Period
Dated 4.031 ± 0.003 Ga

Specimen is a 2.00g slice

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The Acasta Gneiss is a tonalite gneiss in the Slave craton in Northwest Territories, Canada, exposed on an island about 300 kilometres north of Yellowknife. This rock was previously a granitoid that formed 4.2 billion years ago, an age based on radiometric dating of zircon crystals at 4.2 Ga (Tsuyoshi Iizuka, at al., Geology and Zircon Geochronolgy of the Acasta Gneiss Complex, Precambrian Research, 153 (2007) pp. 179 - 208), and was  metamorphosed 4.031  ± 0.003 billion years ago ( Bowring, S.A., and Williams, I.S., 1999. Priscoan (4.00-4.03 Ga) orthogneisses from northwestern Canada. Contributions to Mineralogy and Petrology, v. 134, 3-16).
Formed during the Hadean Eon of Earth's geological history, such rocks are exposed on the Earth's surface in very few places. Acasta could be the oldest rock known on Earth, the discovery of older rocks in Nuvvuagittuq, with a very old Sm-Nd model age for extraction of the original magma from the mantle (3.8 to 4.28 billion years ago) is still under debate.
The Hadean (pronunciation: /'he?di?n/) is a geologic eon of the Earth, and lies before the Archean. It began with the formation of the Earth abut 4.56 billion years ago and ended, as defined by the ICS 4 billion years ago.The geologist Preston Cloud coinedthe term in 1972, originally to label the period before the earliest-known rocks on Earth. W. Brian Harland later coined an almost synonymous term: the "Priscoan period". Other, older texts simply refer to the eon as the Pre-Archean.

 
 
 

 

About Us

The WWMeteorites team (for "WorldWide Meteorites" - Meteorites from around the world) was created in 2003 with the primary goal of traveling around globe in search of these fascinating celestial objects, and make them available for Science... and Collectors. Since 2017, the team has established its base camp on the island of Unst (Shetland, UK).

With four or five trips per year on average, the number of finds (in countries as diverse as Tunisia, Spain, Qatar, the Sultanate of Oman ...) has quickly become important. WWMeteorites therefore collaborates with several laboratories that analyze, and classify the new meteorites, mainly the Museum Fur Naturkunde (Berlin), the CEREGE (University of Aix-Marseille), and the Appalacjain State University (North Carolina). WWmeteorites (under the name of its founder, Fabien Kuntz.)  have already more than 500 meteorites listed in the Meteoritical Society Database.

In order to have a classification and an official referencement established, as well as to allow the long-term research on the meteorites, a part of 20% of each find by WWmeteorites is deposited in a lab
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