List,
I Put together a program telling why certain specimens are from the Moon and some from Mars and how we know. Thought it might be of interest to the list. Any comment or mistakes would be good to hear about so I can correct them. All my best!
--AL Mitterling
Why We Know Certain Meteorites Originate From The Moon Put together by AL Mitterling
*First and most important is we have been to the Moon and gathered samples to compare to the lunar Meteorites we have recovered.
*Most of the lunar surface is feldspathic. Since lunar meteorites are random sampling from the Moon, we see more feldspathic type lunar meteorites than any other type.
*High concentrations of aluminum were found each time the Apollo orbiters were over highland areas, meaning Plagioclase-rich (hence aluminum-rich) anorthosite.
*Only four minerals - plagioclase feldspar, pyroxene, olivine, and ilmenite account for about 98% of the crystalline material of the lunar crust.
*Some of the most common minerals at the surface of the Earth are rare or have never been found in lunar samples. These include quartz, calcite, magnetite, hematite, micas, amphiboles, and certain sulfide minerals. Many terrestrial minerals contain water as part of their crystal structure. Micas and amphiboles are common examples. Hydrated (water containing) minerals have not been found on the Moon.
*Most of the lunar meteorites have 3—6% FeO, thus, these meteorites are entirely consistent with make-up from typical feldspathic highlands.
*The iron vs manganese abundance is a distinctive property of lunar rocks and serves to distinguish them from terrestrial basalts and all other achondrite types.
*The concentration of iron or aluminum serves as a useful chemical classification system in lunar rocks. Lunar meteorites that are mare basalts (like NWA 032) or breccias composed mainly of mare material (EET 87521/96008) are poor in aluminum and rich in iron. In contrast, meteorites from the feldspathic highlands are rich in aluminum and poor in iron.
*Lunar meteorites are achondrites. Achondrites plot on three distinct Oxygen isotope lines (17 and 18 compared to 16). Lunar specimens plot on one, Martian meteorites (SNC's) plot on another and HED's (Vestoids) plot on another distinct one.
*Lunar specimens contain very little iron or metal (much less than 1%) unlike their asteroid counter parts which have a high abundance of metal (exceptions are some other achondrite types). Lunars are not attracted by magnets. Some metal can make it's way into lunar material by impact but is low percentage.
*Age plays a part in identification of lunar material. Highlands areas date between 4.4 to 4.2 b.y. on the average. Some lunar specimens (plutonic) have been dated as old as 4.6 billion years old. The Mare areas show ages between 4.0 b.y. to 3.2 b.y old.
*Rare Earth Elements (15 of them) play important parts in recognizing Lunar material. Lunar material tends to spike positively or negatively in the europium anomalities.
* Concentrations of the alkali elements (potassium, sodium, rubidium, and cesium) are 10 to 100 times lower in lunar rocks than terrestrial rocks. Low concentrations of alkali elements and sulfide-loving (chalcophile) elements are one of the most characteristic features of lunar rocks.
* All lunar samples have very low concentrations of arsenic compared to terrestrial rocks and meteorites. Except for rare felsites, all lunar rocks also have low concentrations of potassium compared to terrestrial rocks.
*Lunar Meteorites(and samples)contain gases (hydrogen, helium, nitrogen, neon, argon, krypton, and xenon)derived from the solar wind with isotope ratios different than Earth forms of the same gases. They contain crystal damage from cosmic rays. They have crystallization ages, determined by techniques involving radioisotopes, that are older than any known Earth rocks.
Sources: Meteorites and Their Parent Planets by Harry Y. McSween Jr. (newest addition) http://epsc.wustl.edu/admin/resources/moon_meteorites.html
--AL Mitterilng
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