APOLLO 16
LUNAR SAMPLE
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Lunar rock sample 60016 was picked up by Apollo 16 astronaut John Young near the Landing Module in the Descartes region of the highlands of the Moon. When collected the rock weighed 4.3 kilograms (9 1/2 lbs), and now has been extensively cut up for study. The piece on display weighs 128 grams (1/4 lbs).
The rock is called a breccia because it is composed of fragments of older rocks. These fragments are all sizes and were broken from the crust of the Moon through collisions with meteoroids from space. The collisions also heated the fragments so they became welded together to form rocks when they were deposited in beds of hot debris. Many of the fragments probably come from rocks that made up the first crust of the Moon when it formed 4600 million years ago. These fragments are the white pieces visible in the rock and are composed of feldspar. Other rock fragments from different layers in the crust are mixtures of several minerals: feldspar, pyroxene, and olivine.
The collisions that produced the large circular basins visible from earth produced this rock about 4,000 million years ago. The rock probably stayed buried in the bed where it was formed until about 2 million years ago, when a relatively small meteoroid (traveling very fast, though) produced the 400 meter (1/4 mile) wide crater South Ray. The bed was broken up and sample 60016 was thrown up onto the surface where it was collected by the astronauts.
Parts of sample 60016 have been studied in about 15 laboratories throughout the world to determine the compositions and ages of materials that formed the early crust of the Moon. Pieces of the rock have also been used to learn about rays and particles given off by the Sun and also coming through space from other stars (cosmic rays). (The magnetic field around the Earth protects us from most rays and particles.) Some of these studies are continuing, but about 80% of the rock is being carefully stored as a reserve for more sophisticated studies as the methods are developed in the future.
Lunar Sample 60016
ROCK TYPE: Breccia
WEIGHT: 4307 g
COLOR: Medium to light gray (N5-N7)
DIMENSIONS: 13 x 16 x 20 cm
SHAPE: Subround with nearly all rounded corners
COHERENCE: lntergranular: Friable; Fracturing: Three Irregular, nonpenetrative fractures
BINOCULAR DESCRIPTION BY: Ridley DATE: 5/10/72
FABRIC: Equigranular matrix
VARIABILITY: Uniform clast distribution
SURFACE: T 10% dust covered. N 50% dust covered, with one large clast, flat. W 50% dust covered, one craggy corner, one surficial fracture, flat. E 85% dust covered. S 10% light dust covered, smooth except for one large clast mold. B 5% light dust covered, 80% dark dust covered.
ZAP PITS: N has two large zaps (1 cm, 0.5 cm); both are glass-filled. T has three large zaps, glass-filled (1, 0.5, 0.5 cm). E has one at junction with T. None on S, W, B.
CAVITIES: Only clast molds, most 0.5 cm. Angular. One cavity on S > 3 cm.
SPECIAL FEATURES: Coarse salt and pepper matrix gives the surface a medium gray color and the very fine grained dust cover gives a light gray color. The matrix is composed principally of finely comminuted lithic fragments with all gradations in both light and dark clasts from unresolved matrix to large angular clasts. Dark clasts slightly dominant, more angular, and attain larger sizes than the others.
Size (mm)
Component
Color
% or Rock
Shape
Dom.
Range
Note
Lithic clast I black 20-30 ang < 0.1 0.1 - 35 1
Lithic clast II white 15 ang to subrd < 0.1 0.1 - 10 2
Mineral clast I white to colorless 0.5 < 0.5 0.1 - 0.8 3
Mineral clast II honey tr < 0.5 4
Mineral clast III pale yellow-green tr < 0.5 5
NOTES:
- Sharp contact with matrix, very dull to resinous luster, and aphyric.
- Sharp contact with matrix. Fine grained sugary luster. Dominantly shattered feldspar grains. No obvious ferromagnesians.
- Blockly single crystals of feldspar.
- Very rare, probably pyroxene.
- Very rare, probably olivins.
THIN SECTION DESCRIPTION BY: Ridley DATE: 6/28/72
SECTION: 60016
SUMMARY: General impression of a breccia that has undergone thermal metamorphism, retaining abundant mineral clasts but converting the matrix into an ophitic, pyromefamorphic texture.
MATRIX, 85 - 90% OF ROCK
Phase
% of Matrix
Shape
Size (mm)
Comments
Cpx 50
polk 1 - 0.5 About 1 mm plates Poikilitic clinopyroxene. Well developed ophitic texture. Plag 45
anh-subhed 0.05 Ilm 5
MINERAL CLASTS 10 - 15% OF ROCK
Phase
% of Matrix
Shape
Size (mm)
Comments
Plag 99
ang 1 - 0.5 No indication of shocked plagioclase or incipient melting. Oliv 0.5
subrded 0.5 - 0.05 Metal 0 - 0.5
rded 0.3
ADDITIONAL COMMENTS: Angular plagioclase clasts contrast with small subhedral plagioclase enclosed within clinopyroxene. Abundant ilmenite tends to be concentrated around edges of clinopyroxene poikocrysts. Also abundant metal, occasionally associated with troilite. Rare brown staining associated with metal.
OPAQUES DESCRIPTION BY: Brett DATE: 6/26/72
SECTION: 60016,14
About 20 rounded grains in the 3µ-to-submicron size range of FeS, Fe-Ni and ilemenite were seen in this section. This makes this near the all-time record for low opaque mineral content in a lunar rock.
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Last Revised: March 19, 2002
Digital Engineering Institute
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