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.[4] [5] As a result, achondrites have distinct textures …

2025年1月18日 · Meteorite - Achondrite, Chondrite, Stony: Achondrites, their name meaning “without chondrites,” are a relatively small but diverse group of meteorites. They exhibit a range of features that would be expected if their parent bodies experienced widespread melting: igneous features similar to those observed in terrestrial volcanic rocks, segregation of molten metal (possibly into a core) from ...

A subset of the achondrites, often referred to as the primitive achondrites, are rocks with broadly chondritic compositions, but with achondritic textures. Almost all achondrites have ages of about 4.6 Ga, essentially identical to the ages of chondrites. Table A1 summarizes the major groups of achondritic meteorites.

If the rock is a breccia that contains iron-nickel metal, then it is a meteorite.Some brecciated achondrites contain iron-nickel metal, but not much, although in a few (e.g., NWA 5000) metal grains can be seen on a sawn face or as rusty spots.I suspect that only a few brecciated achondrites contain enough metal for the rock to attract a magnet. ...

achondrite, any stony meteorite containing no chondrules (small, roughly spherical objects that formed in the solar nebula).The only exclusions are carbonaceous chondrites of the CI group, which, though they are clearly chondrites, are so heavily altered by water that any evidence for their having contained chondrules is lost. Achondrites, constituting about 4 …

Petrography: The meteorite is an enstatite achondrite predominantly composed of 50-1000 µm sized enstatite and less abundant sodic feldspar grains. Some regions appear to be recrystallized exhibiting triple junctions. Albitic and Si-rich glass is present throughout the meteorite. Opaque phases include nodules composed of niningerite and Cr ...

Click on the images below to learn about some of the achondrites in the ASU Center for Meteorite Studies collection! Sign up for Center updates here! Email. Meteorite of the Month. Ipiranga. Ipiranga is an ordinary (H6) chondrite that fell the morning of December 27, 1972, in Brazil. According to the Meteoritical Bulletin (MB 52): “A bright ...

2017年3月3日 · This section covers achondrites and achondritic clasts in stony-iron meteorites (Table 1). Achondrites comprise ~6% of the global collection. Achondrites were derived either from asteroids (asteroidal achondrites) or larger planetary bodies (planetary achondrites) . Asteroidal achondrites are broadly classified into primitive and differentiated ...

As of February 2018 there are approximately 57400 officially classified meteorites [1]. Of these approximately 4000 are classified as achondritic meteorites [1], based on their chemical, mineralogical and textural features. The classification system for the achondrite meteorites is complex and, in some cases remains contentious, with different characteristics seemingly contradicting the models ...

Stony achondritic meteorites constitute approximately 3% of all meteorites. Their parent bodies have undergone considerably more processing than those of the chondrites, but to different degrees. Some, including lunites, shergottites, nakhlites, and chassignites (SNCs), and howardites, eucrites, and diogenites (HEDs) come from the upper mantle ...