Featured Specimens

Howardites are an abundant group of polymict-breccia achondrites that appear to represent mixtures of eucrites + diogenites (these three linked groups are collectively known as HED meteorites and may come from asteroid 4 Vesta). The main minerals in howardites are pyroxene (largely orthopyroxene) and Na-poor plagioclase. A minority of howardites are rich in solar-wind noble gases and thus inferred to be regolith breccias.

Eucrites are the most abundant type of basaltic achondrite, linked by geochemical traits such as oxygen isotopic ratios and certain elemental ratios, of which Fe/Mn is the most widely cited. The main minerals in eucrites are Fe-rich pyroxene and Na-poor plagioclase. The eucrites are strongly linked with the diogenites and howardites; the three groups are collectively known as HED meteorites and may come from asteroid 4 Vesta.

Diogenites are an abundant type of achondrite, linked by geochemical traits such as oxygen isotopic ratios and certain elemental ratios, of which Fe/Mn is the most widely cited. The dominant mineral in diogenites is orthopyroxene. The diogenites are strongly linked with two other achondrite groups: eucrites and howardites; the three groups are collectively known as HED meteorites and may come from asteroid 4 Vesta.

Acapulcoites, named after the Acapulco, Mexico, fall of 1913, (closely related to Lodranites), are equigranular meteorites. Acapulcoites are finer grained than Lodranites and contain rare, relict chondrules, and there are transitional meteorites between the two types. Mineral assemblages are similar to, but distinct from those of ordinary chondrites. Compositions are subchondritic, with lodranites showing a higher degree of fractionation. 20% or more iron content.

Angrites, named after the Angra dos Reis, Brazil, fall of 1869, are a relatively rare type of basaltic achondrite with low alkali contents, high Ca/Al ratios, and a distinctive mineral assemblage, generally including Al-Ca-Ti-rich pyroxene, Ca-rich plagioclase, and Ca-rich olivine that may have exsolved the mineral kirschsteinite.

Aubrites, named after the Aubres, France, fall of 1836, are enstatite achondrites. Most are breccias (Shallowater being a notable exception) containing igneous and impact-melted clasts. Like enstatite chondrites, aubrites have highly reduced mineralogy, but they probably do not come from the same parent asteroid as either EH or EL chondrites.

Brachinites, named after Brachina, a meteorite found in Australia in 1974, are olivine-rich achondrites that are relatively close to chondrites in many compositional properties, and so are frequently considered to be primitive achondrites. Their true origin is still an open question and not all brachinites may share the same origin.

Lodranites, named after the Lodran, Pakistan, fall of 1868, are subchondritic, show a higher degree of fractionation and are coarser grained than Acapulcoites.

Ureilites, named after the Novo-Urei, Russia, fall of 1886, are ultramafic achondrites that contain interstitial carbon as graphite or diamond. The majority consist of olivine + uninverted pigeonite. In a few, the pyroxene is augite and/or orthopyroxene instead. In addition, about 10% of ureilites are polymict breccias, containing a few percent of feldspathic material in addition to typical ureilitic components.

Winonaites, named after the Winona, Arizona, find of 1928, are equigranular rocks, some of which may contain relict chondrules, that have mineralogy and composition that are similar to chondrites.The mineral assemblage is more reduced than that of H chondrites. Winonaites are related to the silicate inclusions found in IAB complex irons.

Lunar meteorites are lunar rocks that were ejected from the Moon by impacts and later fell to the Earth as meteorites.

martian rocks that were ejected from Mars by impacts and later fell to the Earth as meteorites

dunitic cumulate rocks named after the Chassigny, France, fall of 1815

clinopyroxenites or wehrlites, formed as cumulate rocks, and named after the Nakhla, Egypt, fall of 1911

basaltic to lherzolitic igneous rocks, named after the Shergotty, India, fall of 1865

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