Lunar Meteorite: Aridal 019 & 020

possible paired stones

Photos of Aridal 020 by Ziyao Wang. From the description, it is not clears why this rock is so dark. Glassy breccias tend to be dark.

from The Meteoritical Bulletin, No. 111

Aridal 019

Rio de Oro, Western Sahara
Purchased: 2022 February
Mass: 1368 g (5 pieces)

Lunar meteorite (feldspathic breccia)

History: Five similar-appearing stones were found together.

Physical Characteristics: One large stone (1207 g) plus four smaller stones (total 161 g). All stones exhibit a brown, knobby exterior with light desert patina; cut interior surfaces reveal small white to beige clasts within a fine grained tan matrix.

Petrography: (A. Irving, UWS and P. Carpenter, WUSL) Fine grained breccia composed of mineral clasts of anorthite, altered olivine, low-Ca pyroxene, pigeonite and augite in a very fine grained matrix containing low-Ti, high-Al chromite, ilmenite and minor secondary barite. Most olivine has been completely altered to an iddingsite-like hydrous phase with low oxide sums and elevated FeO/MnO ratios; this is very similar to the altered olivine documented in paired lunar meteorites Tisserlitine 001 and NWA 13621.

Geochemistry: Anorthite (An95.9-97.7Or0.1, N = 3), low-Ca pyroxene (Fs28.5-35.0Wo2.0-4.5, FeO/MnO = 60-71, N = 4), pigeonite (Fs31.0-31.9Wo8.1-8.9, FeO/MnO = 57-60), augite (Fs20.1-21.9Wo39.6-35.1, FeO/MnO = 51-53, N = 2), unaltered olivine (Fa39.3, FeO/MnO = 92, N = 1).

Classification: Lunar (feldspathic breccia). Although this material has some mineralogical similarities to Tisserlitine 001 and NWA 13621 found in eastern Mali, these stones have a different external appearance and the find site is reliably at a location much farther to the west.

Specimens: 22.4 g including one polished endcut at UWB; remainder with Mr. T. Boudreaux.

from The Meteoritical Bulletin, No. 112

Aridal 020

Rio de Oro, Western Sahara
Purchased: 2022 November
Mass: 157.1 g (1 piece)

Lunar meteorite (feldspathic breccia)

History: Found in southern Morocco and purchased by Ziyao Wang in November 2022 from a dealer in Ouarzazate, Morocco.

Petrography:  (A. Irving, UWS and P. Carpenter, WUSL) Breccia composed of fairly closely-packed mineral clasts of anorthite, olivine, low-Ca pyroxene, pigeonite, subcalcic augite and augite in a sparse fine-grained matrix containing medium-Ti chromite, ilmenite, kamacite, minor schreibersite (as composite grains with kamacite) and rare silica polymorph. Secondary terrestrial phases are barite and a fibrous chlorite-like phyllosilicate phase with low oxide sums and elevated FeO/MnO ratios replacing some primary olivine.

Geochemistry: Olivine (Fa37.2-43.3, FeO/MnO = 91-96, N = 3), low-Ca pyroxene (Fs18.9Wo3.0, FeO/MnO = 51), pigeonite (Fs22.9-29.7Wo6.2-8.4, FeO/MnO = 50-54, N = 2), subcalcic augite (Fs17.8Wo25.6, FeO/MnO = 39), augite (Fs8.8Wo44.1, FeO/MnO = 34), anorthite (An93.6-97.2Or0.2-0.0, N = 3).

Classification: Lunar (feldspathic breccia).

Specimens: 21.1 g including a polished slice at UWB; remainder with WangZ.

Randy Says…

These two meteorites may be paired. The strongest evidence is the descriptions of the olivines and the fact that they were found 6.3 km apart. Aridal 017 was found 30 km to the southeast.

More Information

Meteoritical Bulletin Database

Aridal 019 | 020