|Latitude & Longitude (WGS84):||30° 19' 0'' North , 4° 56' 34'' West|
|Latitude & Longitude (decimal):||30.31694,-4.94278|
|Other regions containing this locality:||Northwest Africa Meteorites|
Sahara Desert, North Africa
|Locality type:||Meteorite Fall Location|
|Meteorite Class:||Angrite meteorite|
|Meteoritical Society Class:||Angrite|
|Metbull:||View entry in Meteoritical Bulletin Database|
|Köppen climate type:||BWh : Hot deserts climate|
Angrite (Differentiated Achondrite)
Found 2006, 213 g
Northwest Africa 4590 (NWA 4590), a small purchased meteorite find with a fresh crust and mild weathering stains, appears to be a separate and unpaired meteorite — consisting only of impact-shattered fragments of a single meteorite fall. NWA 4590's principle constituents — fassaite [33 vol%], anorthite [28 vol%], fayalitic olivine [14 vol%], and kirschsteinite [5 vol%] — are the usual major constituent of almost all angrites. Its overall inventory of minor constituents is also quite similar to those reported for other angrites. However, unlike almost all recovered angrites, NWA 4590 appears to lack ferric iron. It also appears to have been more completely characterized than several other more massive and/or earlier recovered angrites. Rhönite and pigeonite,for example, have been reported and, more recently, a previously unidentified 'Ca-rich Silico-Phosphate' has been identified as a Si-rich apatite.
NWA 4590 is one of only 23 recorded angrites — a group of differentiated and quite ancient meteorites with high-temperature melt products and isotopic ratios similar to their prototype, Angra dos Reis (stone). While Angra dos Reis is the only angrite fall, it is somewhat unclear how many separate angrite falls are in our collections. 17 angrites from Northwest Africa have been listed at the Meteoritical Bulletin Database (March 2015), but whether they represent only a few falls or, say, 10-12 separate falls is not evident at this time. [Many NWA meteorite fragments have been distributed as purported 'separate' meteorites to enhance sales]
A word of caution. Some reports of apparent Fe-Ni metal in angrites have been labelled as 'kamacite' in published abstracts without accompanying compositional data. As at least some of the metal in angrites is Ni-poor (<2 wt%), it is not clear that such uncharacteristically Ni-poor iron should be given the conventional label for meteoritic iron. Meteoritic iron with an invariable higher Ni-component is found in almost all chondrites and irons. Rare instances of Ni-poor iron in meteorites are reported almost exclusively as tiny secondary phases in some differentiated achondrites.
11 valid minerals.
Meteorite/Rock Types Recorded
Select Rock List TypeAlphabetical List Tree Diagram
Entries shown in red are rocks recorded for this region.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
66 - 145 Ma
|Mesozoic sedimentary rocks|
Age: Cretaceous (66 - 145 Ma)
Lithology: Sedimentary rocks
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. 
66 - 100.5 Ma
100.5 - 145 Ma
|Early Cretaceous undifferentiated|
Age: Early Cretaceous (100.5 - 145 Ma)
Reference: Asch, K. The 1:5M International Geological Map of Europe and Adjacent Areas: Development and Implementation of a GIS-enabled Concept. Geologisches Jahrbuch, SA 3.