Stony-meteorites

Chondrites

Chondrites are the oldest known matter. These meteorites developed simultaneously with our central star, the Sun, by crystalizing out in the presolar primeval nebula in form of ball-like spezies, the so-called chondrules. These chondrules condensed together with other presolar matterl to smaller and larger rocks and remained the following 4,5 billions years more or less unchanged.

Chemically the Chondrites resemble the Sun if one refrains from the missing of all fleeting elements as well as helium and hydrogen. But according to the place, in which the respective Chondrites crystalized out in the presolar primeval nebula they are significantly different, thus numerous groups and clans are distinguished, which further below are described individually.

Next to the separation in clans and groups, Chondrites are generally distinguished according to so-called petrological classes, a scale of 1 to 7 that gives information about the differentiation degree of the individual Chondrites. The classes 1 and 2 occur only in Carbonaceous Chondrites and designate meteorites with sparse, little chondrules in which a change took place through oxidising and water. The class 3 designates meteorites with large, clear chondrules that remained almost unchanged while the classes 4 to 6 designate Chondrites, that increasingly got heated in their history and hereby were changed. The chondrules with higher petrological degree become more and more undifferentiated and fuse with the matrix. The class 7 finally comprises meteorites whose chondric nature becomes clear only through their chemical compound. They contain no more chondrules and form a kind of transition to the Achondrites.

Carbonaceous Chondrites

Ordinary Chondrites

Enstatites, Rumurutis and other Chondrites

 

Achondrites

Carbonaceous Chondrites

New: Microscopical views od Ck 4
 

Carbonaceous Chondrites

The carbonaceous Chondrites, also C-Chondrites, probably represent the oldest well known matter and resemble in their chemical make-up more the Sun than all other Chondrites. Typical is their content of water and minerals, changed by water, their content of carbon and organic compounds as well as the fact, that most of them in the course of their existence scarcely changed by thermal processes. The most primitive Carbonaceous Chondrites in the course of their history never were heated over a temperature of 50 degrees centigrade! In spite of all these commonalities, the Carbonaceous Chondrites are still quite different according to place of origin in the presolar primeval nebula and are subdivided into several groups. The most important are mentioned below:

CI-Chondrites

CI-Chondrites got their name after their fall in Ivuna, Tansania, and only a handful of these rare meteorites is known. They are the most primitive and unsightly meteorites at all- and yet also the most interesting. Petrologically almost all belong to class 1; only one CI 2-Chondrite is known. They contain almost no visible chondrules, however a water content of up to 20% and numerous organic compounds as well as amino acids and other modules of life. Possibly they have their origin in comets, but certainly they come from the external areas of our solar system, which is apparent by the fact, that in the course of their development they never were heated over 50 degrees centigrade.

CM-Chondrites

The numerically better represented group of the CM-Chondrites is named after their fall at Mighei, Ukraine. The CM-Chondrites almost all belong to the petrological class 2. They contain less water than the CI-Chondrites, besides this, in their mineralogical composition they are quite similar to them. Also they contain organic substances, like amino acids, but in addition they possess clearly visible chondrules and frequently inclusions of so-called CAIs (Calcium-Aluminium-Inclusions). These CAIs contain microscopic small diamonds with isotopical signatures, which point not only to a substantially higher age than that of our solar system, but rather it obviously comes from interstellar matter - matter from other star systems, which at the origin of our solar system was included and preserved in the CAIs. Originally, the meteorites of the CM-group could also come from comets; they possibly also are descendants of the largest asteroid in our solar system, 1 Ceres, who shows a very similar reflection spectrum.

CV-Chondrites

CV-Chondrites are named after their fall at Vigarano, Italy, and encompass the petrological classes 3 and 4. In their structure and chemical compound, they resemble more the normal Chondrites, however contain in contrast to these also traces of water, organic substances and especially many big chondrules and CAIs - a typical feature of the CV-group. An especially well known CV-meteorite is the fall of Allende, Mexico, that happened in 1969, shortly before the first manned Moon landing. At that time almost two tons of the rare and scientifically so valuable matter fell on Earth - enough material to equip not only all research laboratories, but rather also all private collectors therewith!

CO-Chondrites

The CO-Chondrites are named after their fall at Ornans, France, and petrologically always belong to the class 3. Chemically they resemble the CV-Chondrites, with whom they form one clan, but they differ already on the first view through their black appearance, their very few chondrules and through substantially less inclusions of CAIs. Moreover they contain clearly visible inclusions of nickel iron, which in polished disks appear as tiny schimmering flakes.

CR-Chondrites

CR-Chondrites were named after the fall of Renazzo, Italy, and belong to the petrological classes 2 and 3. Originally they were incorporated into the CM-group, but in the mean time it is clear that they represent one characteristic group. They possess usually large, clearly distinguished chondrules and contain relatively much nickel iron in contrast to the CM-Chondrites as well as iron sulfide. There is a correspondence of the reflection spectrums of the CR-Chondrites with the second largest ssteroid in our solar system, 2 Pallas, that possibly is the mother body of these very rare Carbonaceous Chondrites.

CK-Chondrites

CK-Chondrites, named after their fall at Karoonda, Australia, encompass the petrological classes 3 to 6 and originally were held for representatives of the CV-group. Cut slices of this meteorite appear, based on a high share of magnetite, usually dull and black, interspearsed by inclusions of differently sized chondrules and occasionally by CAIs. Many CK-Chondrites moreover show shock veins, veins of rock melted by pressure, what refers to an eventful past of the CK mother body and/or on an impact event. Until now the exact place of origin of this very rare meteorites group however has become not sufficiently certain.

CH-Chondrites

This very little group of Carbonaceous Chondrites is exceptionally not named after a fall, but rather after a special characteristic: the "H" stands for "High Iron" and designates the for this group characteristic high share in nickel iron that often can amount to over 50% of the total mass! Alone this fact could suffice to designate the CH-group as a form of Stony-iron meteorite, but the familiarity of the carbon rock share with the meteorites of the CR-group has let to the fact that one incorporated it into the class of the Carbonaceous Chondrites. Petrologically the well known CH-Chondrites all belong to to the group 3, and a not yet clarified narrow connection exists to another group of Chondrites, the Bencubbinites, that are described further below.

 

Ordinary Chondrites

Enstatites, Rumurutis and other Chondrites

 

Achondrites

Ordinary Chondrites

Chondrites of this class are considered as "ordinary" because they represent with more than 85% of all Chondrites the largest part of these meteorites. As a cosmic primeval matter, they are surely anything else than usual. Mineralogically they consist to the large part of olivines and orthopyroxenes as well as a characteristically high share in more or less oxidised nickel iron. Based on this share in iron and other mineralogical charakteristics, they are subdivided in three groups:

H-Chondrites

H-Chondrites, based on their high share of nickel iron, are equipped with the "H", that stands for "High Iron". The meteorites of this group contain a weight share of 25 to 31% iron, whereby 15 to 19% of the iron is in an unbound, metallic form. Consequently H-Chondrites are quite strongly attracted by a magnet. Petrologically the H-Chondrites encompass the classes 3 to 7, and they consist mineralogically above all of Olivine and the Orthopyroxene Bronzite. Based on this fact, they are designated sometimes also as Olivine-Bronzite-Chondritee although this name is obsolete and rarely used. Comparisons of the reflection spectrums of the H-Chondrites with the spectrums of well known asteroids yielded that the H-Chondrites possibly come from the asteroid Hebe or from a descendant of it.

L-Chondrites

The "L" in the L-Chondrites stands for "Low Iron", therefore for a typical iron content of 20 to 25%, whereby however only about 4 to 10% of this iron is in an unbound, metallic form. This fact causes, that L-Chondrites attracted by a magnet, but by far not so strongly as the H-Chondrites. Petrologically the L-Chondrites encompass the classes 3 to 7, whereby the class 6 is represented especially often. Mineralogically L-Chondrites consist of Olivine and the Orthopyroxene Hypersthene, what gave them also the name Olivine-Hypersthene-Chondrites. Also this name today is no longer common although one will find it often in literature. The L-Chondrites could perfectly well come from the earthnear asteroid Eros, a sky body that is examined presently intensively by the space probe NEAR-Shoemaker. The reflection spectrums correspond rather exactly, and perhaps one will soon be able to say with certainty, that the L-Chondrites are descendants of this asteroid.

LL-Chondrites

LL-Chondrites are the rarest of the ordinary Chondrites. The "LL" stands for "Low Iron" and "Low Metal" and takes into account that the LL-Chondrites possess a typical iron amount of 19 to 22%, whereby merely 1 to 3% occur in more metallic, unbound form . Accordingly the LL-Chondrites are only weakly magnetic. As the H and L-Chondrites also the LL-Chondrites encompass all petrological classes from 3 to 7, whereby however noticeably many, original LL3-meteorites get found. In older sources, the LL-Chondrites are designated sometimes as Amphoterites, but this name is no more common and should therefore be avoided. Concerning their origin the LL-Chondrites possibly come from the earthnear asteroid Eros and represent another place of origin on the about 20 km large mother body.

Carbonaceous Chondrites

 

Enstatite, Rumuruti and other Chondrites

 

Achondrites

Enstatit, Rumuruti and other Chondrites

Enstatite Chondrites

Enstatite Chondrites, often also shortly E-Chondrites, are a rare group of Chondrites that differ in many ways the Ordinary Carbonaceous Chondrites. So they must have emerged in a very oxigen sparse environment, because almost all iron in these meteorites appears in reduced metallic form. Also their pyroxen share contains no iron and appears only in form of the magnesium rich Enstatites, a fact that gave them their name. Petrologically the E-Chondrites encompass all classes of 3 to 7, whereby the classes 3 and 6 are represented quite often. As the Ordinary Chondrites, the E-Chondrites are often subdivided also according to their content of iron into lower groups, so that many of them were classified as EH- or EL-Chondrites. Nevertheless all Enstatite Chondrites might come from one and the same mother body. Many researchers suppose that this has to be searched for in close vicinity to the sun, perhaps in the area of the orbit of Merkury because the origin of the E-Chondrites requires an especially oxygen poor, reducing environment. Other researchers assume an origin in the internal area of the Asteroids Belt, and only future researches will bring news about the actual origin of the E-Chondrites to us.

Rumuruti Chondrites

Rumuruti or R-Chondrites were named after the fall at Rumuruti, Kenya, and are in many regards the opposite to the E-Chondrites. However they are similarly rare, but the iron contained in them is almost completely oxidised or exists in form of different iron-sulfides. Also the olivine content in the R-Chondrites is astonishingly iron rich and lends them their dark, often reddish appearance. In comparison with the Ordinary Chondrites in the R-Chondrites relatively few chondrules are found. Petrologically, degrees from 3 to 6 were found, whereby comparatively many R-Chondrites are so-called breccias of different degrees, what suggests an eventful past of the mother body with numerous impacts. In many Rumuruti Chondrites also inclusions of carbon material is found, which is a further indication for the history of the Rumuruti mother-body full of impacts.

Other Chondrites

Next to the better known groups, there are still some other Chondrites classes, of which respectively only a couple of representatives were described. These groups are rather "hypothetical", what means, that they are not completely acknowledged by the modern meteorite science as independent classes. Nevertheless they shall be mentioned here:

Kakangari Chondrites

Kakangari Chondrites, also shortly named K-Chondrites, carry their name after the fall at Kakangari. Petrologically, the meteorites of this group found till now correspond to class 3. Their oxidising degree lies between that of Ordinary-and Enstatite Chondrites, and their unique isotopical signature suggest that they come from one mother body.

Forsterite Chondrites

The Forsterite or F-Chondrites are only known as inclusions in other meteorites and were described by certain lithologies of the Aubrite of Cumberland Falls, USA. Mineralogically, obviously they consist primarily of the olivine end-link Forsterite, what makes them to an unique group. But until now no complete meteorites of this group were found on Earth, and therefore this class is to be considered as hypothetical.

Bencubbinites

The Bencubbinites, sometimes also named B-Chondrites, consist just of a handful of members and were named after the fall at Bencubbin. They contain next to carbon material a lot of iron what made many researchers incorporate them into the category of the Stony-Iron-meteorites. Chemically they are very close to the Carbonaceous Chondrites of the CR-clans and the CH-Chondrites so that it can be assumed, that they crystalized at least in a similar area of the presolar primeval nebula. But it is also possible that they represent samples of different regions of one and the same mother body - possibly it is 2 Pallas, the second largest asteroid in our solarsystem!

Carbonaceous Chondrites

Ordinary Chondrites

 

Achondrites

Achondrites

Achondrites represent a very heterogeneous class of meteorites. They differ from the more frequent Chondrites substantially, first of all by the missing of chondrules, but we have already seen that there are also Chondrites, that possess no chondrules at all, and just like that there is at least one kind of Achondrite that has chondrules. These exceptions mark transitions between both classes that become understandible if we bear in mind, that the Chondrites represent almost unchanged premeval matter from of the origin of our Solar system. Through melting- and recrystallization processes on some asteroids and planets out of the chondric premeval matter emerged differentiated rock, that delivered the basic substance of the Achondrites.

Achondrites therefore are samples of other differentiated worlds and resemble in this earthly stone. Nevertheless, most Achondrites are quite primitive - i.e. are little differentiated - and consequently are very old. They come mostly from the remote time of the origin of our solar system, a time that reaches back between 4,6 and 4,2 billions of years. The reason is, that they come from smaller mother bodies, asteroids, who quickly cooled off after their emergence and therefore became geologically inactive.

Only few Achondrites provable come from larger mother bodies, what expresses also in a substantially younger origin. Planets like our neighbour Mars were (or are) geological active until now, and so it isn't surprising that Mars meteorites were found, that - compared to other meteorites -are astonishingly young with an estimated origin age of only few hundred millions years. These meteorites are correspondingly highly advanced e.g. strongly differentiated and resemble the earthly rock the most.

PAC-group (Primitive Achondrites)

The symbol "PAC" stands for "Primitive Achondrites" and comprises different groups of meteorite that are quite similar to their chondritic precursors in chemistry and structure. They are little differentiated and emerged probably on very small asteroids, that became melted by impact happenings and then recrystalized very fast.

Acapulcoites

This small class was named after a fall that happened in 1976 in the environment of Acapulco, Mexico. Originally this meteorite was classified as an anomalous Chondrite, but after in the following decades some similar meteorites were found, one recognized that it concerns a class of primitive Achondrites, that marks the transition between chondritic basic substance and differentiated rock. That fourteen until now known Acapulcoites consist mainly of Olivine and Pyroxene and slighter shares of plagioclase, metallic nickel iron and troilite. In lots of Acapulcoites also intact chondrules were found, what underlines once again that this group represent a scarcely differentiated mother body and is to be regarded as the maybe most primitive class of Achondrites.

Lodranites

Lodranites, named after the fall at Lodran, Pakistan in 1868, were originally coinsidered as a small group of Stony-iron meteorites because they consist approximately to same parts of Olivine and Pyroxene as well as finecrainy nickel iron. Only the discovery of the Acapulcoites led, based on great chemical and isotopic resemblance, to incorporate them into the group of the Primitive Achondrites. Probably Acapulcoites and Lodranites come from the same little differentiated mother body, a little asteroid, who's chemistry shows some relations with the mother bodies of the E- and H-Chondrites.

Brachinites

The Brachinites are a very small group of olivine rich, Primitive Achondrites and were named after their find at Brachina, Australia. This meteorite was first of all classified as a Chassignite, a rare type of Mars meteorite ,but as one examined it and further six similar finds more exactly, one assessed that it concerns one characteristic class of Primitive Achondrites, that resemble the Chassignites only in their mineralogical composition. In comparison to the relatively young Mars rock, the Brachinites are with an origin age of 4,5 billions of years very old and show an entire other pattern in their trace elements, that show a typically chondritic distribution.

Winonaites

The Winonaites represent a further rare class of primitive Achondrites and were named after an unusual find. The meteorite Winona was discovered 1928 in archaeological excavations in the prehistoric Elden-Pueblo, Arizona, in a wall niche chiseled into the stone. Obviously it had served the indians living here as a sanctuary after perhaps they even had observed its fall. And also for science, Winona became somewhat entirely special, the prototype of a new meteorites class, that differs in its isotopic signature very clearly from all other Achondrites. A narrow relationship exists to the Iron meteorites of the chemical class IAB. Many IAB-irons contain Silikate inclusions, that resemble a lot the Winonaites, and probably come both from one and the same mother body.

Primitive Enstatite Achondrites (Zaklodzies, ITQIYs)

Next to the Acapulcoites/Lodranites,the Brachinites and Winonaites there is another series of further Primitive Achondrites, that however are each more or less individual finds and therefore don't justify the set up of a new class. Examples for this are two lately found, enstatite rich Achondrites: Zaklodzies out of Poland and ITQIYs out of North Africa. Both are unique in chemistry and mineral substance and consist mainly of Enstatite and metallic nickel iron. Somehow Zaklodzies remind in their structure the Acapulcoites, while the ITQIYs structurally are similar to the Lodranites. Possibly Zaklodzies and ITQIYs are descendants of one and the same, little differentiated mother body, whose development was similar to the mother body of the Acapulcoites and Lodranites. Further investigations and new finds will probably give more information in the future about this question.

Angrites

The Angrites, named after the fall at Angra dos rice, Brazil, represent a very small class of differentiated Achondrites with only six members, that consist of pyroxene, olivine and plagioclase. In contrast to the Chondrites and Primitive Achondrites, these minerals however exist in forms, that are typical for a magmatic origin: the pyroxene exists mainly in form of the mineral fassait, that olivine contains next to iron and magnesium also calcium, and the plagioclase exists almost exclusively as a calcium rich anorthite. Also the general structure as well as frequently appearing round vesicals, that are considered as hardened gaz bubbles, let the Angrite appear as typical discharge rock, i.e. as a basalt magmatic origin, that are quite similar to earthly basalts. With the difference that the Angrites with an origin age of about 4,56 billions of years are very old! The origin of this primeval basalt however is now as ever a riddle. Based on certain isotopic resemblances one assumed at times, that the Angrites like the meteorites of the HED-group came from the asteroid 4 Vesta. But based on their high age and certain differences in the chemistry one assumes today that the Angrites must come from a separate mother body, not yet identified so far.

Aubrites

The Aubrites were named after the fall at Aubres, France, where in 1836 an about 800 g heavy meteorite went down. Based on its peculiar mineralogical structure, the Aubrites are considered also as Enstatite Achondrites, because to the large part they consist out of this almost iron free, magnesium rich Pyroxene. Next to Enstatite the strongly brecciated Aubrites contain also different parts of reduced nickel iron, Olivine, Troilite and some rare minerals, that let assume on a magmatical origin under reducing conditions. In spite of a chemical resemblance to the Enstatite Chondrites and Primitive Enstatite Achondrites, the Aubrites certainly come from another mother body, that endured a substantially stronger differentiation. Spectrological investigations have identified the asteroid 44 Nysa and some of its companions as possible mother bodies, whereby above all an outsider out of this asteroids family, the erdnear asteroid 3103, moved in point of view. Possibly this nameless asteroid with about 1,5 kms of diameter is the origin of all Aubrites existing on Earth. Forty-six of these rare meteorites were described until now.

Ureilites

The Ureilites, named after the fall at Novo Urei, Russia in the year 1886, are the probably most mysterious Achondrites in general. They consist mainly of Olivine and Pyroxene in a carbon rich matrix out of graphite, diamond, reduced nickel iron and Troilite. Both the chemical and the isotopical investigations of the Ureilites led to contradictory results: some facts let the Ureilites appear as a highly differenciated kind of rock while other results move these meteorites more into the region of the Primitive Achondrites. Based on these contradictions, until now there is no theory generally acknowledged about the emergence and the origin of the Ureilites. Nevertheless most researchers agree, that the high carbon content suggests some relations to the Carbonaceous Chondrites, and that the Ureilites probably come from a differentiated asteroid of the C-class. Until now ninety-five of these mysterious meteorites were found, what makes the Ureilites to one of the "more frequent" Achondrites classes.

HED-group ("Vestameteorites")

The HED-group consist of three different classes of closely related Achondrites, that Howardites, Eucrites and Diogenites, whose initials form the symbol "HED". From their mineralogical composition and origin these meteorites are quite different, but their almost identical chemical and isotopical structure show very clearly that all three must come from one and the same mother body. Comparisons of the reflection spectrums of these meteorites with the spectrums of various asteroids yielded that this mother body concerns probably of the main belt-asteroid 4 Vesta, one of the largest asteroid in our solar system (see origin). For this reason the meteorites of the HED-group are sometimes also namrd "Vestameteorites".

Diogenites

The Diogenites were named after the Greek philosopher Diogenes, that already in the fifth century before Christ assumed that meteorites don't come from Earth, but rather from the cosmos. Mineralogically the Diogenites, of which ninety-six falls and finds are known, are of differentiated depths rock, that consist above all of magnesium rich, calcium scarce orthopyroxene. They contain beside it also smaller quantities of olivine and plagioclase, but the main part of the mass are the often large pyroxene crystals, that again are typical for plutonic rock that formed itself in magma chambers in the coat of a planet or asteroid, and were able to grow up by slow cooling to such a size. The Diogenites are therefore samples of magmatic processes that happened about 4,4 billions years ago within their mother body Vesta!

Eucrites

The term Eucrite comes of the Greek word eukritos that means something like "to distinguish easily". The old meteorites science lent the Eucrites, that form the numerically largest Achondrites class with more than two hundred falls and finds, this name out of two reasons: first because they can be distinguished by their appearance easily from the Chondrites, and secondly, because they resemble certain earthly rock of volcanic origin, that were also named Eucrites at that time. Today this name is only common only for the meteorites of the same name although the Eucrites remind actually in various regard to the terrestric basalts. They consist of calcium rich plagioclase (anorthite), calcium scarce pyroxene and often contain shares of reduced nickel iron, what makes many Eucrites a bit magnetic. Often they contain also small vesicles, that are considered as hardened gas bubbles and underline the magmatic origin of the Eucrites as real discharge rock once again. Eucrites are the basalts of another world, comparably with the basalts, that formed and still form on Earth through volcanic activity.

Howardites

The Howardites were named after the British chemist Edward Howard, a pioneer of the meteorite science (see history), and today ninety-five falls and finds of this rare class are known. In certain regards the Howardites form a kind of link between Diogenites and Eucrites, that however - not as one could assume -emerged in the coat of the Vesta, but rather at its surface. The Howardites are, considered mineralogically, a Regolith rock: baked together "dust layer" from the surface of their mother body in which about same parts of diogenitic and eucritisc rock with chondric impact matter from space mix. And so one finds in the strongly brecciated Howardites also most different inclusions of smaller and larger meteorites, that fell in the course of the billions of years on Vesta and with by them set free and by the solar wind pulverized Eucrites and Diogenites combined to new rock. This natural variety makes the Howardites not only to some of the most interesting, but also to some of the prettiest Achondrites in general.

LUN-group ("Moonmeteorites")

The symbol "LUN" comes from "Lunaite" and represents a group of Achondrites, that come from our Earth satellite, the Moon (see also origin). If one exactly looks at the Moon in a starlit night, one can well imagine, how these meteorites arrived from the surface of the Moon on the Earth: the Earth satellite is strewn with large craters of impacts, that had enough power to eject rocks from its crust and accelerate them such that they got through the field of gravity of the Moon and landed in the cosmos. Some of these fragments got into an unstable orbit around our planet and after some time fell as Moon meteorites on the Earth. These meteorites are of course as different as the rocks on the Moon. Until now twenty-four Moon meteorites were found worldwide, that can be classified into five different classes:

Anorthositic regolith highlandland breccias

The Regolith Highlandbreccias are the majority of the well known Moon meteorites with more than ten finds. They come from the highlands of the Moon, that form the largest part of its surface, and dominate mainly the from the Earth invisible side. In their mineral consistence, they consist mainly of regolith that emerged through meteorite bombardement and solar wind, a baked together dust, containing numerous clasts of original plagioclase that as a calcium rich anorthosite is the primary rock forming mineral on the highlands of the moon. This composition gives the anorthositic regolith highland breccias their typical appearance with angular, white clasts (anorthite) in a carbonaceous-black matrix (regolith).

Fragmental highland breccias

The fragmental highland breccias, of which until now only two are known, also origine from the highlands of the moon. However they don't consist of regolith, but rather out of brecciated rock fragments from underneath the lunar surface. Thus they consist mineralogially mostly of anorthosite, the calcium rich plagioclase from the lunar highlands, as well as of some other extra minerals e.g. pyroxene and olivine.

Impact-melt breccias

The breccias, of which also only two finds are known, resemble in their mineralogical compound the other lunaites of the highlands with the difference that some minerals contained in them exist in strongly shocked form, i.e. became changed in their structure by an earlier impact event. Thus in these impact-melt breccias also frequently glass veins of shocked rock as well as high pressure minerals are found.

Marebasalts

These meteorites of which only five are known are samples of the lunar mares, the large, dark basins, that form the lowlands of the moon. Three of these five moon meteorites are regolith breccias, that show comparing them with the regolith highlandbreccias only fragments of the original basalts in a regolith-matrix, while in two of these meteorites it concerns of real samples of the lunar marebasalts. These consists mainly of the pyroxene Pigeonite and Augite as well as a smallerr share of plagioclas and olivine.
In contrast to the highland rock, the Mare basalts are by far younger rock, taking into account that the lunar mares came into existence only about a billion years after the about 4,5 billions year old highlands.

Mare gabbros

This class is represented only by one meteorite find from the Antarctica, the meteorite asuka-881757, that in its coarse-grained structure represents the only unbrecciated moon meteorite well known until now. Mineralogical it is a so-called gabbro, a rock, that consists primarily of the minerals plagioclase (in the form of Anorthite) and pyroxene (Pigeonite and Augite). It remains to be seen whether in the future further samples of this material are discovered and other until now not known lunar rocks in the form of meteorites!

SNC-group ("Marsmeteorites")

The rare SNC-meteorites, that were named after the initials of three historic falls: Shergotty, Nakhla and Chassigny, form a further group. These meteorites are summarized with some further falls and finds based on mineralogical and chemical resemblances into one group, and in the mean time it is rather certain that all these meteorites come from our neighbour planet Mars (see also origin). For this assumption indicates not only the comparably young age of most of the SNC-meteorites, that often is only few hundred millions years, but rather also a comparison of gases included in this meteorites with the results of the Viking-probes, which examined in the year 1976 the exact composition of the Mars atmosphere. In the mean time twenty-two of this "Mars meteorites" are known, that stem however probably out of only seventeen falls. Basically the SNC-meteorites subdivide themselves into four mineralogical classes :

Shergottites

The Shergottites, named after the fall at Shergotty, India, are among the Mars meteorites especially frequent and make out seventeen of the twenty-two well known SNC-meteorites. Mineralogically they split into two different types, into the basaltic and into the lherzolithic Shergottites. The basaltic Shergottites consist mainly of plagioclase and pyroxene and resemble earthly basalts of volcanic origin. The iherzolithic Shergottites consist of olivine and orthopyroxene and contain only slighter quantities of plagioclase. They are closely related to the basaltic Shergottites, but represent no discharge rock, but rather pluto depths rocks of the Mars, that came out of the same magma layers like their basaltic relatives. But there are also transitions between the basaltic and lherzolithic type, that for example are represented by the Mars meteorites out of the Dhar al Gani desert, Libya.

Nakhlites

The Nakhlites are named after the fall at Nakhla, Egypt, and only three of these finegrainy, greenish brown meteorites are known. In the mineralogical sense, they consist mainly of calcium rich pyroxene (augite) and a slight share of olivine. Interestingly enough, recently in the Nakhlites one discovered rare minerals that could only emerge in the presence of fluid water. Analyses yielded that these minerals must have emerged still being on Mars, what means that our red neighbour still possessed at least at the moment of origin of the Nakhlites, therefore about 1,5 billions years ago, fluid water and perhaps even oceans!

Chassignites

Closely related with the Nakhlites are the Chassignites that were named after the only representative of this class, the meteorite Chassigny, France. Mineralogically in Chassignites it concerns of a so-called dunite, a depths rock consisting almost purely out of olivines. Also in Chassignites, traces of minerals were found, that were able to emerge only in the presence of water, so for example the on Earth also well known amphibol.

Orthopyroxenites

Also this group is represented only by one representative, by the antarctic meteorite ALH84001. In contrast to the other Mars meteorites it consists almost exclusively of orthopyroxene and possesses a substantially higher age. Especially wellknown became this hottly discussed meteorite by numerous investigations of various inclusions, that indicate a - at least earlier - primitive life on our neighbour planet Mars (see sensations).

Chondrites