Moon rock

Moon rock or lunar rock is rock originating from Earth's Moon. This includes lunar material collected during the course of human exploration of the Moon, and rock that has been ejected naturally from the Moon's surface and landed on Earth as meteorites.

For other uses, see Moonrock.

Dating[edit]

Rocks from the Moon have been measured by radiometric dating techniques. They range in age from about 3.16 billion years old for the basaltic samples derived from the lunar maria, up to about 4.44 billion years old for rocks derived from the highlands.^[22] Based on the age-dating technique of "crater counting," the youngest basaltic eruptions are believed to have occurred about 1.2 billion years ago,^[23] but scientists do not possess samples of these lavas. In contrast, the oldest ages of rocks from the Earth are between 3.8 and 4.28 billion years.

The ferroan anorthosite suite consists almost exclusively of the rock (>90% calcic plagioclase) with less common anorthositic gabbro (70-80% calcic plagioclase, with minor pyroxene). The ferroan anorthosite suite is the most common group in the highlands, and is inferred to represent plagioclase flotation cumulates of the lunar magma ocean, with interstitial mafic phases formed from trapped interstitial melt or rafted upwards with the more abundant plagioclase framework. The plagioclase is extremely calcic by terrestrial standards, with molar anorthite contents of 94–96% (An94–96). This reflects the extreme depletion of the bulk Moon in alkalis (Na, K) as well as water and other volatile elements. In contrast, the mafic minerals in this suite have low Mg/Fe ratios that are inconsistent with calcic plagioclase compositions. Ferroan anorthosites have been dated using the internal isochron method at circa 4.4 Ga.

anorthosite

The magnesian suite (or "Mg-suite") consists of (>90% olivine), troctolites (olivine-plagioclase), and gabbros (plagioclase-pyroxene) with relatively high Mg/Fe ratios in the mafic minerals and a range of plagioclase compositions that are still generally calcic (An86–93). These rocks represent later intrusions into the highlands crust (ferroan anorthosite) at round 4.3–4.1 Ga. An interesting aspect of this suite is that analysis of the trace element content of plagioclase and pyroxene requires equilibrium with a KREEP-rich magma, despite the refractory major element contents.

dunites

The alkali suite is so-called because of its high alkali content—for Moon rocks. The alkali suite consists of alkali with relatively sodic plagioclase (An70–85), norites (plagioclase-orthopyroxene), and gabbronorites (plagioclase-clinopyroxene-orthopyroxene) with similar plagioclase compositions and mafic minerals more iron-rich than the magnesian suite. The trace element content of these minerals also indicates a KREEP-rich parent magma. The alkali suite spans an age range similar to the magnesian suite.

anorthosites

Lunar granites are relatively rare rocks that include , monzodiorites, and granophyres. They consist of quartz, plagioclase, orthoclase or alkali feldspar, rare mafics (pyroxene), and rare zircon. The alkali feldspar may have unusual compositions unlike any terrestrial feldspar, and they are often Ba-rich. These rocks apparently form by the extreme fractional crystallization of magnesian suite or alkali suite magmas, although liquid immiscibility may also play a role. U-Pb date of zircons from these rocks and from lunar soils have ages of 4.1–4.4 Ga, more or less the same as the magnesian suite and alkali suite rocks. In the 1960s, NASA researcher John A. O'Keefe and others linked lunar granites with tektites found on Earth although many researchers refuted these claims. According to one study, a portion of lunar sample 12013 has a chemistry that closely resembles javanite tektites found on Earth.

diorites

Lunar breccias range from glassy vitrophyre melt rocks, to glass-rich breccia, to regolith breccias. The vitrophyres are dominantly glassy rocks that represent impact melt sheets that fill large impact structures. They contain few clasts of the target lithology, which is largely melted by the impact. Glassy breccias form from impact melt that exit the crater and entrain large volumes of crushed (but not melted) ejecta. It may contain abundant clasts that reflect the range of lithologies in the target region, sitting in a matrix of mineral fragments plus glass that welds it all together. Some of the clasts in these breccias are pieces of older breccias, documenting a repeated history of impact brecciation, cooling, and impact. Regolith breccias resemble the glassy breccias but have little or no glass (melt) to weld them together. As noted above, the basin-forming impacts responsible for these breccias pre-date almost all mare basalt volcanism, so clasts of mare basalt are very rare. When found, these clasts represent the earliest phase of mare basalt volcanism preserved.

Discoveries[edit]

Three minerals were discovered from the Moon: armalcolite, tranquillityite, and pyroxferroite. Armalcolite was named for the three astronauts on the Apollo 11 mission: Armstrong, Aldrin and Collins.

A visitor touching a lunar sample at the Kennedy Space Center Visitor Complex

NASA Lunar sample 15555 on display at Space Center Houston Lunar Samples Vault, at NASA's Johnson Space Center

NASA Lunar sample 15498 on display at Space Center Houston Lunar Samples Vault, at NASA's Johnson Space Center

NASA Lunar sample 60015 on display at Space Center Houston Lunar Samples Vault, at NASA's Johnson Space Center

NASA Lunar sample 60016 on display at Space Center Houston Lunar Samples Vault, at NASA's Johnson Space Center

NASA Lunar Sample Return Container with Lunar soil on display at Space Center Houston Lunar Samples Vault, at NASA's Johnson Space Center

Lunar Ferroan Anorthosite #60025 (Plagioclase Feldspar). Collected by Apollo 16 from the Lunar Highlands near Descartes Crater. This sample is currently on display at the National Museum of Natural History in Washington, DC

Samples in Lunar Sample Building at JSC

Moon rock on display for visitors to touch at the Apollo/Saturn V Center

Sample collection case, containing collection bags for use on the surface, at the National Museum of Natural History

Tongs used to pick up Moon rocks

A piece of regolith from Apollo 11 presented to the Soviet Union and exhibited in the Memorial Museum of Cosmonautics in Moscow.

Apollo 17 "Goodwill Moonrock"

Cut fragment of Apollo 17 sample 76015, an impact melt breccia

Sample 15016, the Seatbelt basalt

Apollo 16's sample 61016, better known as Big Muley, is the largest sample collected during the Apollo program

Big Bertha, collected on Apollo 14, is among the largest rock samples returned from the Moon (nearly 9 kilograms)

Moon rocks on display at the National Museum of China

Marc Norman (April 21, 2004). . Planetary Science Research Discoveries.

"The Oldest Moon Rocks"

Paul D. Spudis, The Once and Future Moon, Smithsonian Institution Press, 1996, 1-56098-634-4.

ISBN

—Johnson Space Center

Rocks & Soils from the Moon

Archived September 28, 2006, at the Wayback Machine

Apollo Geology Tool Catalog

Archived April 13, 2011, at the Wayback Machine—Washington University, Department of Earth and Planetary Sciences

Lunar meteorites

Lunar and Planetary Institute

Lunar Samples

educational journal

Articles about Moon rocks in Planetary Science Research Discoveries

collectSPACE

Where Today are the Apollo 11 Lunar Sample Displays?

collectSPACE

Where Today are the Apollo 17 Goodwill Moon Rocks?

Kentucky's lunar sample displays in the Kentucky Historical Society objects catalog: , Apollo 17