An achondrite is a type of stony meteorite whose precursor was of chondritic origin and experienced metamorphic and igneous processes. They have a planetary or differentiated asteroidal origin where the chondritic parent body reached a sufficient size that through heating due to radioactive decay of 26Al (aluminum isotope) and gravitational meteorites from the surface of the Moon. Most were found in the hot deserts of northern Africa and Oman and others were found in the cold desert of Antarctica, although one, a 19-gram specimen, was recovered in 1990 from Calcalong Creek, Australia. These stones are of great importance because, in many cases, they provide specimens of the Moon from regions not visited by the manned Apollo or unmanned Russian sample-return missions. Most were blasted out of the The highly cratered, topographically high, ancient crust of the Moon. This region is composed mostly of anorthosite, a plagioclase-rich rock. rather than the low-lying Broad low plains surrounded by basin-forming mountains, originally thought to be a sea (pl. maria). This term is applied to the basalt-filled impact basins common on the face of the Moon visible from Earth. , which served as the Apollo landing sites.
The lunar meteorites found so far, represent four distinct types of Moon rock and are categorized into groups LUN A (anorthositic highland breccias), LUN B (Broad low plains surrounded by basin-forming mountains, originally thought to be a sea (pl. maria). This term is applied to the basalt-filled impact basins common on the face of the Moon visible from Earth. basalts), LUN G (Work in progress Coarse-grained igneous rock of basaltic composition that formed at depth and is 90% plagioclase. clinopyroxene, https://www.sandatlas.org/gabbro/ The most important mineral groups that make up this rock type are plagioclase and pyroxene. Plagioclase usually predominates over pyroxene. Plagioclase is sodium-calcium feldspar. It contains more calcium than sodium in gabbro. If there is), and LUN N (Igneous rock composed of 90% plagioclase, 95% orthopyroxene (low-Ca pyroxene) and less than 10% olivine. Norite is most commonly found in the lunar (highlands) meteorites but has also been found in about a dozen diogenites, a few shergottites, and a very small number of other achondrite types. Gabbro is very). One interesting specimen is a LUN B Work in progress. A solid natural object reaching a planet’s surface from interplanetary space. Solid portion of a meteoroid that survives its fall to Earth, or some other body. Meteorites are classified as stony meteorites, iron meteorites, and stony-iron meteorites. These groups are further divided according to their mineralogy and, found in Morocco in 2000, that crystallized from Hot molten or semifluid rock derived from a volcano or surface fissure from a differentiated and magmatically active parent body. just 2.8 Ga ago and provides evidence for surprisingly recent lunar volcanism.
The only known LUN N meteorite, found in three pieces near Dchira in the Western Sahara and named NWA 773, is especially important because it represents a type of rock never sampled by the Luna or Apollo landing missions, but detected from The elliptical path of one body around another, typically the path of a small body around a much larger body. However, depending on the mass distribution of the objects, they may rotate around an empty spot in space • The Moon orbits around the Earth. • The Earth orbits around at several sites on the surface. The Aitken basin, a large impact structure near the lunar South Pole that is famous for its noritic composition and secondary impact craters, is a possible source of NWA 773. The large impact that excavated the Aitken basin removed the upper Outermost layer of a differentiated planet, asteroid or moon, usually consisting of silicate rock and extending no more than 10s of km from the surface. The term is also applied to icy bodies, in which case it is composed of ices, frozen gases, and accumulated meteoritic material. On Earth, the, exposing lower crustal layers that contain olivine-rich norites and gabbronorites.
All lunar meteorites can be considered mixtures of mare basalts and highlands rocks as shown by their bulk chemistries when plotted on a FeO vs. Al2O3 diagram.
Some or all content above used with permission from J. H. Wittke.