NORTHWEST AFRICA 12971


Lunar Feldspathic Breccia
(troctolitic melt rock)
standby for nwa 12971 photo
Purchased April 2019
no coordinates recorded

A single vesicular stone weighing 280 g was purchased by M. Lyon and two partners from a Moroccan dealer. A sample was sent for analysis and classification to the University of Washington in Seattle (A. Irving) and Washington University in St. Louis (P. Carpenter), and NWA 12971 was classified as the first lunar troctolitic melt rock.

The meteorite has a very fine-grained (µm-scale) shock-melt texture and is composed primarily of anorthite and olivine, together with accessory pigeonite, augite, chromite, troilite, and pyrrhotite. In the diagram below, the line dividing troctolites and norites represents the proportions of olivine and pyroxene that define a ratio of 1:1 (Taylor et al., 1991).

Major Mineral Modes for Lunar Rocks
lunar modes
click on photo for a magnified view

Diagram credit: Taylor et al., Lunar Sourcebook, ch. 6: Lunar Rocks, p. 215, (1991 open access link)
Cambridge University Press; Grant H. Heiken, David T. Vaniman, Bevan M. French, eds.

The specimen of NWA 12971 pictured above is a 3.58 g partial slice that contains small scattered relict clasts of various compositions. Shown below is a 7.09 g slice containing a large relict coarse-textured clast.

standby for nwa 12971 photo
Photo shown courtesy of Mark Lyon