Newsletter |
40,1 |
Location |
Larkman Nunatak |
Field Number |
23140 |
Dimensions (cm) |
2.0 x 4.5 x 3.0 |
Weight (g) |
59.20 |
Original Classification |
EH3 Chondrite |
Updated Classification |
EL3 Chondrite |
Ferrosilite (mol%): 0-7 |
A |
A/B |
Black fusion crust covers the exterior of this enstatite chondrite, fractures and minor amounts of reddish/orange rust are visible. The interior is a dark groundmass with minor amounts of orange rust and shiny metals are visible throughout. |
The section shows an aggregate of chondrules (up to 1 mm), chondrule fragments, and pyroxene grains in a matrix of about 30% metal and sulfide. Chondrules contain minor abundances of olivine. Weathering is minor. Microprobe analyses show the pyroxene is Fs0-7 and that the Fe,Ni metal contains 3 wt. % Si. The meteorite is an EH3 chondrite. |
LAR 12156 was classified in AMN 40, no. 1 as an EH3 chondrite. Analyses originally reported for the FeNi metal phases included 3 wt% Si. A detailed study of the metal and sulfide phases found that the metal contained < 1.4 wt% Si, and in the range of EL chondrites (Anzures, 2021). In addition, Anzures (2021) found alabandite to be present in the section which is also more consistent with classification as an EL chondrite (niningerite being more common in EH3). In this newsletter (AMN 47, 1) are presented metal analyses with FeNi containing 1.4 wt% Si (average of 10 analyses). Based on the observations of Anzures (2021) and the follow-up analyses FeNi metal in the library section at SI, we now re-classify LAR 12156 as an EL3 chondrite.
Anzures, B. (2021) Volatiles and Redox in Mercury and Chondritic Parent Bodies: Insights from Experiments and Laboratory Analyses of Meteorites, Ph.D. Thesis. Brown University. |