Pristine Sample Laboratory Display Cabinet
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A display cabinet is located at one end of the Pristine Laboratory. It
contains one Apollo 16 and two Apollo 15 samples which are representative of the rocks in the lunar
sample collection. Note that this cabinet represents one exception to the rule that samples from
different missions are not housed in the same cabinet at the same time. |
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15459, a 5.9 kg rock, was collected just inside
the rim of a 100-meter diameter crater on the foot of the mountains overlooking the Apollo 15 landing
site. The rock is a tough, coherent regolith breccia - composed of rock fragments and other soil
components such as small glass spheres and glass shards bonded together in a glassy matrix. Breccias
such as 15459 are formed in ancient regoliths by meteorite impacts in which heat and pressure bond
rock fragments and soil particles together. Impacts not only fuse rocks from regolith particles, but
break rocks into small fragments and fling these fragments and blobs of molten glass some distance
into the surrounding area. Rock fragments, called clasts, found inside breccias like 15459, can
represent material thrown from the surrounding areas by prior impacts. Clasts in 15459 are diverse;
some are mare basalts from the lava-filled plains and others are from the older highlands. One basalt
clast crystallized 3.3 billion years ago, although the age of formation of the breccia now called
15459 might be as recent as 500 million years ago or less. |
| 15556, a 1.5 kg rock, was
plucked from near the rim of Hadley Rille at the Apollo 15 site. From the rim of Hadley, astronauts
could see layers of basalt exposed in the wall of the rille, which is interpreted as an ancient lava
channel. This medium grained, extremely vesicular basalt is 3.4 billion years old. Since the Moon
is so very dry, the volatile gas causing the vesicles (bubble cavities) in this rock and other rocks
probably was a mix of oxides of carbon and sulfur dissolved in the molten rock. |
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61016, at 11.7 kg, was the
largest rock collected during the Apollo missions. It was nick-named "Big Muley" after one member of
the geology support team. Apollo 16 landed in the light-colored highlands of the Moon. These
highlands regions are generally higher in elevation and composed of older rocks relative to the
volcanic plains. These rocks are rich in aluminum and calcium, two of the elements found in the
plagioclase mineral anorthite. This specimen is comprised of four different rock types: 1) material
of basaltic composition melted during an impact; 2) an impact-shocked anorthosite, thought to be from
ancient lunar crust; 3) an impact shock-melted glass rich in aluminum and calcium; and 4) a darker
glass coating. Some components in this rock may be as old as 4.5 billion years. Zap pits, or tiny
craters created by micrometeorites striking the lunar surface at very high speeds, are prominent on
one side of this rock, but absent on the other. Since the pitless side was facing up when the
astronauts found the rock, it must have only recently been turned over by natural processes. |
