Lunar sample 12002,320.
This mature highlands soil was collected by the Apollo 16 mission to the lunar highlands southwest of Mare Tranquillitatis. The soil was sieved to remove the small size fraction. It is mostly made of feldspathic breccias, agglutinates, feldspar fragments, and occasional mare basalt fragments.
Magnification key 20x = 8 mm image width 40x = 4 mm image width 100x = 1.6 mm image width 200x = 0.8 mm image width 400x = 0.4 mm image width 500x = 0.32 mm image width |
40X, plane polarized light.
Low magnification view of a variety of fragment types in this soil. Most of the dark, porous-looking fragments are agglutinates. The dark, homogeneous fragments are glass and partially devitrified glass. A mare basalt pyroxene fragment is in the bottom center, and a mare basalt fragment is in the lower right. There are several feldspathic breccias, which are light-colored with a fragmental texture. Five obvious ones are at top center, bottom just to the left of center, and three more on the left.
40X, cross polarized light.
The feldspathic breccia fragment in the top center and the lower left fragment are very feldspathic, probably anorthositic. In contrast, the other three, especially the larger one toward the upper left, contain considerable mafic material with relatively low birefringence and are probably norite breccias.
100X, plane polarized light.
Closeup views of three somewhat foamy, dark agglutinate grains. The grain at the top center appears to be a norite breccia, and the large single crystal at the lower left is a mare basalt pyroxene grain.
100X, cross polarized light.
The agglutinate grains are mostly isotropic glass and opaques (including iron), but contain a variety of mineral and devitrified glass fragments.
100X, plane polarized light.
Another variety of fragments. The striking fragment just to the left of center appears to be an impact melt breccia with poikilitic clinopyroxene. The colorless grain at the top center is a shocked plagioclase, an agglutinate is at the top left and probably top right. A partially devitrified glass fragment is at the bottom center, and partially annealed noritic breccias are at the bottom left and also just below and to the left of center. The amoeboid thing in the lower right is a vapor bubble in the epoxy mounting medium.
100X, cross polarized light.
The optically continuous character of the pyroxene in the large, bright impact melt breccia fragment is obvious, as are the relic angular fragments of unresorbed plagioclase. In contrast, the feldspathic breccias at the lower left and just below and to the left of center are largely unannealed.
100X, plane polarized light.
Partially devitrified glass fragment.
100X, cross polarized light.
Partially devitrified glass fragment. Needles appear to be both pyroxene and plagioclase.