A meteorite is a rock from space that passes through the atmosphere and survives impact with the ground. Most meteorites
originate from larger asteroid bodies orbiting the Sun in the asteroid belt
between Mars and Jupiter. Collisions and gravitational interactions between
asteroids can send smaller pieces into the inner solar system where they
can intersect with Earth's orbit to become part of the thousands of
meteorites that fall to earth. The Earth collides with thousands of small
pieces of this material from outer space producing the sporadic shooting
stars and fireball meteors seen at night. Several larger meteoroids collide
with the Earth every day with some landing in the oceans and others on land.
A meteor is the streak of light we see at night as a small meteoroid
burns up passing through our atmosphere. A fireball is a very bright meteor
and may actually break up and drop meteorites. Meteors and fireballs are
commonly referred to as shooting stars. In addition, each year the
Earth passes through the orbits of comets and the dust from these comets
produce a meteor shower. Meteor showers happen as tiny bits of material
from dust size to the size of a grain of wheat. They burn up almost completely
high in the atmosphere dozens of miles above the Earth's surface. It's
important to note that some people call these events meteorite showers but
this is not accurate as meteor shows do not produce meteorites.
There are three basic types of meteorites, the irons, stony, and the
stony-irons. Each of these basic families has subgroups.
The iron group is nearly solid nickel-iron metal. Because of the
strength of the metal, some of the largest individuals recovered are
iron. Also many of the craters formed by
iron meteorites because the asteroids
survived without breaking up all the way to the ground. Magnets strongly
attract Iron meteorites which look like real metal when you grind a
spot off their surface. They show a pattern when etched by chemicals
because of the different nickel-iron minerals composing them.
The stone type of meteorite is almost completely rocky material and
are also the most common type. There are dozens of subgroups in this
family. The simplest breakdown of the stony group is, Chondrites, Achondrites,
and the Planetary meteorites containing the achondrites that have unique
A chondrite meteorite
is a rock from space that contains small spherical structures called
chondrules. These are droplets of melted rock which cooled in microgravity
into tiny spheres. The chondrules clumped up and through accretion
formed into larger masses, finally becoming asteroid-size bodies
from which broken off chunks have made it to Earth. All meteorites
contain the same elements as here on Earth but new minerals form
because the processes of rock creation in space are quite different
from those on Earth. The elements are able to combine to form some
minerals not found in terrestrial rocks. However, most of the minerals
in meteorites are those that make up terrestrial rocks as well.
Most chondrites have nickel-iron metal in them. The metal can be
as little as a few percents to as much as twenty-five percent or
more. The tiny chondrules of chondrites hold together by finer grain
particles that form a matrix. Heat from various sources has liquefied
the chondrules and particles into rock, and heat can also alter
the meteorite's character over time.
Achondrites are stone meteorites that do not have chondrules.
If you heat a achondrite
meteorite until it completely melts and then let it coll and
recrystallize, it will leave no trace of the chondrite structure.
Another way they form as rocks on larger bodies with sufficient
size to squeeze and melt the rocks. This is what occurs at depths
in the Earth creating our igneous rocks. The achondrites like the
chondrites can have iron metal in them. The achondrite subgroups
of the Howardites, Eucrites, and Diogenites may be from the large
The planetary achondrites are meteorites that have come from
the Moon and Mars. We recognize lunar
meteorites because of their similarity to the Moon rocks returned
to Earth by the Apollo astronauts. The
Martian meteorites have small
amounts of trapped gas that matches the gases in the Mars atmosphere.
Someday we may find space rocks from the other rocky planets of
the inner solar system. We may even identify some that are pieces
of the Earth due to impacts from long ago. These would likely be
the hardest to identify since only by examining the fusion crust
or someone seeing them fall would distinguish them from normal Earth
rock outside a laboratory.
Stony Iron Meteorites
The stony-irons are a mixture of nearly 50% rock and 50% nickel-iron
metal. The two subgroups of the
stony-iron meteorites are the pallasites, which contain olivine
crystals as the rock component, and the mesosiderites which contain
various silicate minerals as the rock portion. In both of these types,
the metal portion completely surrounds the rock portion. In other words,
the metal is not in veins or isolated chunks but as the matrix enclosing
the mineral half of the mass. The stony-iron family is the rarest of
the three main groups and they are among some of the most beautiful
of all the meteorites.
Meteorite Identification Tests
Meteorites are the rarest types of rock on Earth. People send thousands
of rocks to laboratories each year by individuals thinking that they found
a meteorite. At best only one or two of these thousands is actually a rock
from space. This article teaches people the basic characteristics of how
to identify a meteorite. This guide provides simple at home tests that can
help the reader to make a better determination if their rock is truly a
space rock, or one of many terrestrial rocks known as meteor-wrongs. The
pictures in the section below will help answer the question of what do meteorites
All meteorites fall through the atmosphere at such high velocity
that material burns off their exterior. This melting leaves a glassy
outer coating called a fusion crust. The fusion crust is usually a dark
gray to charcoal black in color. Black fusion crust can be shiny or
a dull velvety texture. The fusion crust can have lines and flow marks
from the movement of the molten rock across the surface. It is very
common for meteorites, even fresh ones, to have a fusion crust with
chips. Over time with weathering very little of the fusion crust may
Can You Tell Which Stone Has Fusion Crust?
Meteorites are not round balls, and most have irregular shapes. They
are often angular with rounded off corners. Some show pits on their
surface which we call thumbprints. Scientists call these marks regmaglypts,
and they form as hot air currents erode the rock as it plunges through
the atmosphere. People often find old rusty iron masses and confuse
them for meteorites. Cannonballs and mill balls are often the sources
of these meteor-wrongs. These rusty objects have an iron meteorite appearance,
and chemical testing can help determine if they are man-made. The iron
in meteorites is a nickel alloy and if the rock does not contain nickel,
it is not an iron meteorite.
Can You Tell Which Stone Has a Meteorite Shape?
Meteorites are Solid, not Porous
The slag from industrial processes of manufacturing iron and steel
can have metallic particles in it. Slag is one of the materials that
is often confused for meteorites. This slag, however, will usually be
porous or even bubbly which is a clue that it is not a real space rock.
Meteorites, in some cases, may exhibit vesicles, but they are not porous
or bubbly in appearance. Meteorites are solid rocks and may have pits
on their surface, but inside they are dense. Volcanic rocks, basalts,
and lavas are porous and are often mistaken for space rocks.
Which Are Meteorites?
When meteorites are fresh, they are often black, and their fusion
crusts may show flow lines and details that can help in identification.
After a long time on the ground, they can change color, and fusion crusts
wear away, and details disappear. The iron in meteorites just like iron
in tools rusts from being out in the weather. As the iron metal rusts,
it stains the inside rock matrix and the outside surface. Starting as
spots of red or orange on the black fusion crust as time goes on the
whole stone will become rusty brown colored. The fusion crust will often
still be visible but no longer black.
Can You Tell Which Stones Are Meteorites by
Meteorites are Heavy and Have Metallic Iron
Meteorites are generally heavier than earth rocks of the same size.
This is because of the metallic iron that most of them contain. Many
meteorite hunters carry a diamond file with them to grind a small spot
off rocks to see if there are any iron grains inside. With only a few
rare exceptions metallic iron metal is not found in earth rocks. During
eons of erosion and weathering, the iron in earth rocks is now in mineral
form, and not metallic. The metal found in meteorites will be shiny
and look like chrome. The appearance of the metal will not be a shiny
gray sheen, that is often seen on some Earth rocks. Iron metal grains
in rocks can also look like a space rock and are good indicators. However,
there are more tests and many other factors to take into consideration.
The vast majority of meteorites contain some metallic iron while
others are mostly solid iron. This iron makes most space rocks responsive
to a magnet. Many stone meteorites will hold a strong magnet placed
on them even if they are of a low iron type. This magnet test is one
of the first simple tests that can be done at home or in the field.
Rare earth magnets are inexpensive, and available from many sources,
and they are the best for this test. But, there are earth rocks that
also will hold a magnet and to make matters worse they are quite common.
The two most often misidentified rocks are those that contain the minerals
hematite and magnetite. These rocks can sometimes also look a little
like meteorites, and other simple tests can rule these rocks out.
Both Magnets Stick. Which One Is The Meteorite?
It is a common practice in geology to rub a mineral or rock across
a streak test plate and observe the color of the mineral powder line
that is made. This is very useful for examining suspect space rocks
as well. Meteorites will give a brown streak when rubbed on a test plate.
The two most commonly misidentified rocks as mentioned earlier are magnetite
and hematite. The streak color of hematite is a dark red. In fact, the
coloring for rouge used in cosmetics was derived from crushed hematite.
The streak color of magnetite is black. So even though the stone is
responsive to a magnet, the mineral's streak and lack of actual metal
will reveal that it is terrestrial. You do not need to obtain an actual
testing plate to make the streak. The non-glazed back side of a white
ceramic tile will work fine for the test and can be obtained inexpensively.
Which File Shows The Correct Color Streak?
The largest group of space rocks is the chondrite type of stone meteorite,
and they contain nickel-iron metal in the form of tiny grains scattered
throughout the matrix of the rock. There are man-made rock-like materials
such as slags that may have bits of metal, but they will not have a
solid rock-like appearance. If the stone is fresh and has a nice fusion
crust it may not be desirable or even necessary to cut or grind off
a spot to look for metal grains as the appearance of the fusion crust
may be enough evidence of its cosmic origin. But, for example, if the
stone is an old desert rock that is brown and meteorite like in appearance,
you can first grind away a spot with a diamond file. Then, using a hand
lens, look for metal grains to help determine if it is a space rock.
Because the grains are made of iron and can rust, it is common for them
to be altered, or somewhat absent in old weathered stone meteorites.
Very old chondrite stones will still reveal some metal grains upon careful
inspection. If you think it is a meteorite and you see no metal grains
on the small spot you grind with a diamond file, it is a good idea to
bring the stone home and do more tests. A small number of stone meteorites
produce a gray powder when you grind them, and it is wise to bring these
suspects home as well for further testing if they have other identifying
Which Stone Contains Metal Grains?
Meteorite Test Results
Nothing is more important in learning to identify meteorites than seeing
many images of real space rocks. Over thousands of years of weathering on
Earth's meteorites change so much it can become hard to recognize them.
Fresh meteorites have a lot more clues to help in their recognition. We
have many images on our site that can help familiarize the reader with how
true meteorites look. Real space rocks are found every year by hikers and
hunters and others who spend time out of the city. But, the vast majority
of rocks thought to be meteorites are in fact earth rocks. Learning the
characteristics of identifying meteorites is a challenging task, but it
can be accomplished with a little study.
Think you may have found a meteorite?
A Colorado based company offering meteorite testing services called
Geo Labs is a good place to start if you want to find out for sure. For
about a hundred dollars they offer XRF analysis services for the specific
meteorite identification. They use state of the art X-Ray Fluorescence
technology to determine elemental compositions of a sample. Geo Labs is
a good option for the first stage of the identification process.
They can also assist with the more rigorous analysis and classification
processes leading to publication in the Meteoritical Bulletin.
Can you buy meteorites for sale?
Yes, you can legally purchase a
meteorite for sale and collecting them is a fun and fascinating hobby.
They are scientifically interesting and many have amazing stories attached
to them. There are many different ways to start collecting. We recommend
starting small with a broad focus and then you can become more narrowly
focused on which specimens to buy as your expertise grows.