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An achondrite [1] is a stony meteorite that does not contain chondrules. [ 2 ] [ 3 ] It consists of material similar to terrestrial basalts or plutonic rocks and has been differentiated and reprocessed to a lesser or greater degree due to melting and recrystallization on or within meteorite parent bodies.
However, there are significant differences between R chondrites and ordinary chondrites: R chondrites have much more dusty matrix material (about 50% of the rock); they are much more oxidized, containing little metallic Fe–Ni; and their enrichments in 17 O are higher than those of ordinary chondrites. Nearly all the metal they contain is ...
Primitive achondrites are a subdivision of meteorites. They are classified on the same rank (historically called "Class") and lying between chondrites and achondrites . They are called primitive because they are achondrites that have retained much of their original chondritic properties.
Stony meteorites are then traditionally divided into two other categories: chondrites (groups of meteorites that have undergone little change since their parent bodies originally formed and are characterized by the presence of chondrules), and achondrites (groups of meteorites that have a complex origin involving asteroidal or planetary ...
Again, different kinds of chondrites contain different ranges of chondrule sizes: they are smallest in CH, CM, and CO chondrites (see meteorite classification), moderately large in CR, CV, L, LL, and R chondrites, and largest in some CB chondrites (see table). Other chondrite groups are intermediate between these.
Dr. Jenna Podjasek, MD, a board-certified immunologist, allergist and author, explains that the reason why adults older than 65 are at an increased risk for RSV is because the functionality of the ...
Carbonaceous chondrites or C chondrites are a class of chondritic meteorites comprising at least 8 known groups and many ungrouped meteorites. They include some of the most primitive known meteorites. The C chondrites represent only a small proportion (4.6%) [1] of meteorite falls.
This, together with the low content of metal, led the 19th century mineralogist Tschermak to determine that they formed a transitional stage between chondrites and achondrites and to name them amphoterites. [2] We know now that LL chondrites and achondrites are quite different, so this name is no longer in use. Many of the LL chondrites are ...