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Apollo 17 Lunar Samples

The overall set of lunar samples collected during the Apollo program can be classified into three major rock types, basalts, breccias, and highland crustal rocks. Apollo 17 collected important examples of all three rock types. Apollo 17 landed in the Taurus-Littrow valley on the eastern edge of Mare Serenitatis. There were two main geology objectives for this site: to obtain samples of ancient rocks from the lunar highlands crust and to look for evidence of young volcanic activity on the valley floor. The Apollo 17 crew collected 741 individual rock and soil samples totaling 110.5 kilograms, including a deep drill core that included material from 3 meters below the lunar surface. These samples addressed both major pre-mission objectives.

Mare Volcanism

Rocks from the floor of the Taurus-Littrow valley are mostly mare basalts. Basalt consists primarily of the minerals plagioclase and pyroxene and is formed from molten lava. These basalts formed from material that melted at depths of at least 130 to 220 kilometers and then rose to the surface before solidifying. Most of the Apollo 17 mare basalts formed between 3.7 and 3.8 billion years ago. Like the Apollo 11 basalts, the Apollo 17 basalts generally contain large amounts of the element titanium, which is contained in the mineral ilmenite. A few rare Apollo 17 basalts have very low titanium abundances. Seismic and gravity observations indicate that the basalt layer is between 1.0 and 1.4 kilometers thick near the Apollo 17 landing site.

Mare basalts were emplaced as fluids that flowed easily across the Moon's surface. However, photographs taken from lunar orbit suggested that some explosive volcanic activity had also occurred in this region, and some geologists thought this activity might have occurred recently in lunar history. Shorty Crater was explored to determine if it was actually a volcanic vent. Orange and black volcanic glass (the famous "orange soil") was found near the rim of Shorty Crater and did form in an explosive volcanic eruption. On Earth, such eruptions are sometimes called fire fountains. However, the relationship between Shorty Crater and the volcanic glass is just coincidental. The glass formed 3.64 billion years ago from material that melted about 400 kilometers below the surface. Shorty Crater turns out to be an ordinary impact crater, and the lack of degradation of its features indicates that the crater is much younger than the glass.

moon rock collected at Camelot Crater

Apollo 17 basalt 75015, collected at Camelot Crater, has a mass of 1.0 kilograms and consists primarily of the minerals pyroxene, plagioclase, and ilmenite. It has relatively coarse mineral grains, 1-2 mm across, reflecting its cooling and solidification below the lunar surface. The reference cube in this and the other photographs on this webpage is 1 cm across.

Impact Melt Breccias at the North and South Massifs

The Serenitatis basin formed from the impact of a large asteroid or comet with the Moon. The Taurus Mountains surrounding the Apollo 17 landing site were pushed up by this impact. Impact breccias from the younger Imbrium basin impact were later deposited on top of the Taurus Mountains. Many of the rocks from the South Massif landslide at Stations 2 and 3 and from the boulders that rolled down the North Massif at Stations 6 and 7 are impact melt breccias from one of these two large impact events. The shock of these basin-forming impacts melted many rocks and fused many fragments of older rocks together into impact melt breccias. The Imbrium impact occurred between 3.91 and 3.83 billion years ago. The age of the Serenitatis impact is uncertain, with estimates ranging between 4.22 and 3.93 billion years ago.

moon rocks being measured

Left: Apollo 17 sample 73255 from Station 3 is a fine-grained impact melt breccia with a mass of 394 gm. In addition to the impact melt, it contains numerous clasts of various compositions that pre-date the impact event that created the breccia.

Right: Apollo 17 sample 76215 is an impact melt breccia from the large boulder at Station 6. It has a mass of 644 gm. It contains numerous vesicles, which are small holes in the rock created when the material was melted during either the Imbrium or Serenitatis impact events.

Rocks from the Deep Crust

The Apollo 17 crew also collected several rare types of lunar rock, including norite, troctolite, and dunite, at stations 2, 6, and 8 near the base of the North and South Massifs and the Sculptured Hills. Norite consists primarily of the minerals plagioclase and orthopyroxene. Troctolite consists primarily of plagioclase and olivine, and dunite is nearly pure olivine. Many of these rocks originally formed in the lower half of the Moon's crust during the solidification of the Moon’s magma ocean. These rocks formed between 4.2 and 4.5 billion years ago (the solar system formed about 4.56 billion years ago). They were later brought to the Moon's surface by large meteorite impacts, such the impact that formed the Serenitatis basin.

moon rocks being measured

Left: Apollo 17 sample 76535 is a troctolite with a mass of 155 gm. It is an igneous rock and consists primarily of plagioclase (grayish-white) and olivine (greenish-brown), whose coarse grain size (2-3 mm) indicates crystallization and cooling at great depth in the crust. It was collected as part of the rake sample from the regolith at Station 6.

Right: Apollo 17 sample 78235 is a 199 gm norite sample from a small boulder at Station 8. It consists primarily of yellow-brown orthopyroxene and bluish-gray plagioclase. The plagioclase has mostly been converted to maskelynite glass. The coarse grain size indicates crystallization at significant depth in the crust and the maskelynite indicates that the rock reached shock pressures of at least 300-400 kilobars when ejected to the lunar surface by the Serenitatis impact.

Collecting Moon Rocks describes the tools and procedures used by the Apollo astronauts to collect lunar samples.

The Lunar Sample Laboratory at the Johnson Space Center stores the lunar samples and distributes them to qualified researchers for study.

The Lunar Sample Compendium at the Johnson Space Center summarizes the scientific findings of studies of the Apollo lunar samples.

 Return to Apollo 17 main page

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