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Northwest Africa 4801 meteorite (NWA 4801), Northwest Africa Meteoritesi
Regional Level Types
Northwest Africa 4801 meteorite (NWA 4801)Meteorite Fall Location
Northwest Africa MeteoritesMeteorite Fall Location

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Key
Lock Map
Latitude & Longitude (WGS84):
31° North , 4° West (est.)
Estimate based on other nearby localities or region boundaries.
Margin of Error:
~56km
Meteorite Class:
Meteoritical Society Class:
Köppen climate type:


Plutonic angrite (achondrite)
Find, 2007; 252 g


The Northwest Africa 4801 (NWA 4801) was found in 2007 as a single, but friable stone which broke int0 4 pieces. Clinopyroxene and pure anorthite are most prominent, but olivine, pleonaste, merrillite and minor troilite are also found. Early forming olivine is enclosed by clinopyroxene which is in turn surrounded by the anorthite and merrillite. The Ca-rich olivine, anorthite, and Al-Ti rich clinopyroxene are markers of the rather rare angrite class with its various Ca-Al-Ti-rich phases and other chemical signatures. Angrites are also ancient rocks with somewhat distinguishable crystallization ages of ~4.56 billion years. NWA 4801 is a little unusual among the angrites as it both lacks kirschsteinite (usually found in angrites) and is significantly richer in merrillite than other angrites. This may be due to its formation in a somewhat deeper and hotter initial magmatic environment than most other angrites. Minor amounts of kamacite — found in some but not all angrites — shows signs of weathering.

The terminology for NWA 4801’s Al,Ti-rich clinopyroxene varies somewhat in the references cited here and in the literature. Some authors prefer the terms ‘Fassaite’ and ‘Diopside’ but there seems to be no clear consensus.

Regions containing this locality

African PlateTectonic Plate
Sahara Desert, North AfricaDesert
Northwest Africa MeteoritesMeteorite Fall Location

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List


9 valid minerals.

Meteorite/Rock Types Recorded

Note: this is a very new system on mindat.org and data is currently VERY limited. Please bear with us while we work towards adding this information!

Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

Anorthite
Formula: Ca(Al2Si2O8)
Description: Pure; Encloses Clinopyroxene; Some aggregates
Reference: Weisberg et al., (2008) Meteoritical Bulletin, no. 94: Meteoritics and Planetary Science 43 (9): 1551-1588. (Sept 2008) ; Anorthite, Diopside, Olivine; Merrillite, Pleonaste, Spinel, Troilite
Celsian
Formula: Ba(Al2Si2O8)
Reference: Riches, A.J.V. et. al. (2012) Rhenium–osmium isotope and highly-siderophile-element abundance systematics of angrite meteorites. Earth and Planetary Science Letters 353-354: 208-218, Angrite Appendix.
'Clinopyroxene Subgroup'
Description: Al-Ti rich.
Reference: Weisberg et al., (2008) Meteoritical Bulletin, no. 94: Meteoritics and Planetary Science 43 (9): 1551-1588. (Sept 2008)
Diopside
Formula: CaMgSi2O6
Description: enriched in both Al & Ti
Reference: Anorthite, Diopside, Olivine; Merrillite, Pleonaste, Spinel, Troilite
'Fayalite-Forsterite Series'
Reference: Weisberg et al., (2008) Meteoritical Bulletin, no. 94: Meteoritics and Planetary Science 43 (9): 1551-1588. (Sept 2008) ; Anorthite, Diopside, Olivine; Merrillite, Pleonaste, Spinel, Troilite
Goethite
Formula: α-Fe3+O(OH)
Reference: Riches, A.J.V. et. al. (2012) Rhenium–osmium isotope and highly-siderophile-element abundance systematics of angrite meteorites. Earth and Planetary Science Letters 353-354: 208-218, Angrite Appendix.
Iron
Formula: Fe
Reference: Weisberg et al., (2008) Meteoritical Bulletin, no. 94: Meteoritics and Planetary Science 43 (9): 1551-1588. (Sept 2008) ; Riches, A.J.V. et. al. (2012) Rhenium–osmium isotope and highly-siderophile-element abundance systematics of angrite meteorites. Earth and Planetary Science Letters 353-354: 208-218, Angrite Appendix.
Iron var: Kamacite
Formula: (Fe,Ni)
Reference: Weisberg et al., (2008) Meteoritical Bulletin, no. 94: Meteoritics and Planetary Science 43 (9): 1551-1588. (Sept 2008) ; Riches, A.J.V. et. al. (2012) Rhenium–osmium isotope and highly-siderophile-element abundance systematics of angrite meteorites. Earth and Planetary Science Letters 353-354: 208-218, Angrite Appendix.
Merrillite
Formula: Ca9NaMg(PO4)7
Description: Poikilitic
Reference: Weisberg et al., (2008) Meteoritical Bulletin, no. 94: Meteoritics and Planetary Science 43 (9): 1551-1588. (Sept 2008) ; Anorthite, Diopside, Olivine; Merrillite, Pleonaste, Spinel, Troilite; Riches, A.J.V. et. al. (2012) Rhenium–osmium isotope and highly-siderophile-element abundance systematics of angrite meteorites. Earth and Planetary Science Letters 353-354: 208-218, Angrite Appendix.
Spinel
Formula: MgAl2O4
Reference: Anorthite, Diopside, Olivine; Merrillite, Pleonaste, Spinel, Troilite
Spinel var: Pleonaste
Formula: (Mg,Fe)Al2O4
Description: Pleonaste and Cr-Pleonaste appear as two distinct varieties or phases in this meteorite
Reference: Weisberg et al., (2008) Meteoritical Bulletin, no. 94: Meteoritics and Planetary Science 43 (9): 1551-1588. (Sept 2008) ; Anorthite, Diopside, Olivine; Merrillite, Pleonaste, Spinel, Troilite
Tetrataenite
Formula: FeNi
Reference: Riches, A.J.V. et. al. (2012) Rhenium–osmium isotope and highly-siderophile-element abundance systematics of angrite meteorites. Earth and Planetary Science Letters 353-354: 208-218, Angrite Appendix.
Troilite
Formula: FeS
Reference: Weisberg et al., (2008) Meteoritical Bulletin, no. 94: Meteoritics and Planetary Science 43 (9): 1551-1588. (Sept 2008) ; Anorthite, Diopside, Olivine; Merrillite, Pleonaste, Spinel, Troilite

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Iron1.AE.05Fe
var: Kamacite1.AE.05(Fe,Ni)
Tetrataenite1.AE.10FeNi
Group 2 - Sulphides and Sulfosalts
Troilite2.CC.10FeS
Group 4 - Oxides and Hydroxides
Goethite4.00.α-Fe3+O(OH)
Spinel4.BB.05MgAl2O4
var: Pleonaste4.BB.05(Mg,Fe)Al2O4
Group 8 - Phosphates, Arsenates and Vanadates
Merrillite8.AC.45Ca9NaMg(PO4)7
Group 9 - Silicates
Anorthite9.FA.35Ca(Al2Si2O8)
Celsian9.FA.30Ba(Al2Si2O8)
Diopside9.DA.15CaMgSi2O6
Unclassified Minerals, Rocks, etc.
'Clinopyroxene Subgroup'-
'Fayalite-Forsterite Series'-

List of minerals arranged by Dana 8th Edition classification

Group 1 - NATIVE ELEMENTS AND ALLOYS
Metals, other than the Platinum Group
Iron
var: Kamacite
1.1.11.1(Fe,Ni)
Tetrataenite1.1.11.3FeNi
Group 2 - SULFIDES
AmXp, with m:p = 1:1
Troilite2.8.9.1FeS
Group 6 - HYDROXIDES AND OXIDES CONTAINING HYDROXYL
XO(OH)
Goethite6.1.1.2α-Fe3+O(OH)
Group 7 - MULTIPLE OXIDES
AB2X4
Spinel7.2.1.1MgAl2O4
Group 38 - ANHYDROUS NORMAL PHOSPHATES, ARSENATES, AND VANADATES
(AB)3(XO4)2
Merrillite38.3.4.4Ca9NaMg(PO4)7
Group 65 - INOSILICATES Single-Width,Unbranched Chains,(W=1)
Single-Width Unbranched Chains, W=1 with chains P=2
Diopside65.1.3a.1CaMgSi2O6
Group 76 - TECTOSILICATES Al-Si Framework
Al-Si Framework with Al-Si frameworks
Celsian76.1.1.4Ba(Al2Si2O8)
Unclassified Minerals, Mixtures, etc.
Anorthite-Ca(Al2Si2O8)
'Clinopyroxene Subgroup'-
'Fayalite-Forsterite Series'-
Iron-Fe
Spinel
var: Pleonaste
-(Mg,Fe)Al2O4

List of minerals for each chemical element

HHydrogen
H Goethiteα-Fe3+O(OH)
OOxygen
O AnorthiteCa(Al2Si2O8)
O MerrilliteCa9NaMg(PO4)7
O Spinel (var: Pleonaste)(Mg,Fe)Al2O4
O DiopsideCaMgSi2O6
O SpinelMgAl2O4
O CelsianBa(Al2Si2O8)
O Goethiteα-Fe3+O(OH)
NaSodium
Na MerrilliteCa9NaMg(PO4)7
MgMagnesium
Mg MerrilliteCa9NaMg(PO4)7
Mg Spinel (var: Pleonaste)(Mg,Fe)Al2O4
Mg DiopsideCaMgSi2O6
Mg SpinelMgAl2O4
AlAluminium
Al AnorthiteCa(Al2Si2O8)
Al Spinel (var: Pleonaste)(Mg,Fe)Al2O4
Al SpinelMgAl2O4
Al CelsianBa(Al2Si2O8)
SiSilicon
Si AnorthiteCa(Al2Si2O8)
Si DiopsideCaMgSi2O6
Si CelsianBa(Al2Si2O8)
PPhosphorus
P MerrilliteCa9NaMg(PO4)7
SSulfur
S TroiliteFeS
CaCalcium
Ca AnorthiteCa(Al2Si2O8)
Ca MerrilliteCa9NaMg(PO4)7
Ca DiopsideCaMgSi2O6
FeIron
Fe Iron (var: Kamacite)(Fe,Ni)
Fe Spinel (var: Pleonaste)(Mg,Fe)Al2O4
Fe TroiliteFeS
Fe Goethiteα-Fe3+O(OH)
Fe TetrataeniteFeNi
Fe IronFe
NiNickel
Ni Iron (var: Kamacite)(Fe,Ni)
Ni TetrataeniteFeNi
BaBarium
Ba CelsianBa(Al2Si2O8)

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Weisberg et al., (2008) Meteoritical Bulletin, no. 94: Meteoritics and Planetary Science 43 (9): 1551-1588. (Sept 2008)
Irving, A. J. & Kuehner, S. M. (2007) Plutonic Angrite NWA 4801 and a Model for the Angrite Parent Body Consistent with Petrological and Chronological Constraints: Workshop on the Chronology of Meteorites and the Early Solar System. LPI Contribution No. 1374: 74-75.
Riches, A. J. V., Day, J. M. D., Liu, Y., Simonetti, A., Neal, C. R. & Taylor, L. A. (2012). Mineralogical and trace-element constraints on the petrogenesis of Angrites. Lunar Planetary Science Conference XLII, pdf#2229.
Riches, A.J.V., Day, J.M.D., Walker, R.J. Simonetti, A., Liu, Y., Neal, C.R. & Taylor , L.A. (2012) Rhenium–osmium isotope and highly-siderophile-element abundance systematics of angrite meteorites. Earth and Planetary Science Letters 353-354: 208-218, Angrite Appendix.

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