Dhofar 461

• Classification：moon meteorite - achondrite
• Year found：2001/4/22
• Place found：Dhofar, Oman

Unlike the Earth, the Moon has no atmosphere, so it is directly exposed to solar winds. Rocks on the surface of the Moon absorb elements from these solar winds, such as helium. We can often identify helium in meteorites from the Moon.

Dhofar 019

• Classification：martian meteorite - achondrite
• Year found：2000/1/24
• Place found：Dhofar, Oman

The gases contained within Dhofar 019 have been investigated using a method called isotope analysis.* The meteorite was identified as being from Mars, because the gases match those found in the Martian atmosphere.
Observing it with an electron microscope allows us to see not just its shape, but the distribution of elements inside it. Looking at the elemental distribution of Dhofar 019, we can see olivine (iron and magnesium) particles surrounded by plagioclase (aluminum and sodium). This is because after the entire object was melted, the olivine formed first, and the plagioclase formed later in the spaces between it. Only large objects in space can have this kind of structure.

*Atoms of the same element that have a different mass number are known as isotopes. Isotope analysis allows us to closely analyze the amount of isotopes present in an object or substance.

NWA 869

• Classification：stony meteorite - chondrite
• Year found：discovered in 2000
• Place found：Sahara Desert

The round particles contained in this meteorite are believed to have formed 4.6 billion years ago when the solar system was created, so they can provide us with information about this period.

Chelyabinsk

• Classification：stony meteorite - chondrite
• Year found：fell on February 15, 2013
• Place found：Chelyabinsk, Russia

A meteorite that fell in Russia in February 2013, and which contains round particles.
At 100× magnification, you can see cavities on the surface of the meteorite. It is thought that when meteorites enter the Earth's atmosphere they melt and cool very quickly, so pockets of air become trapped inside, creating this structure.
Magnifying it further allows us to see needle-like shapes. At 10,000× magnification, we can clearly see tree-like dendritic patterns (dendrite crystals). These dendrite crystals are believed to have been formed when the meteorite rapidly melted and cooled on entering Earth's atmosphere.

Allende

• Classification：carbonaceous chondrite - CV3
• Year found：fell on February 8, 1969
• Place found：Allende, Chihuahua, Mexico

1969, the year that humans first set foot on the moon with the Apollo program, was also a big year for meteorite research, with events such as meteorite discoveries in the Antarctic.
The Allende meteorite, which contains organic matter, also fell in Mexico in February that year. At the time, an object containing organic matter falling from space was a shocking event.
The white parts are rich in aluminum and calcium (they are known as CAI: calcium-aluminum-rich inclusions) and are believed to be the oldest materials in the solar system.
The CAI research first carried out on the Allende meteorite continues to this day, with new minerals discovered every year.

Aguas Zarcas

• Classification：carbonaceous chondrite - CM2
• Year found：fell on April 23, 2019
• Place found：Aguas Zarcas, San Carlos, Costa Rica

A meteorite containing organic matter. Its composition is thought to resemble that of the asteroid Ryugu, which the asteroid survey spacecraft Hayabusa 2 visited in 2018, and which contained both organic matter and hydrous minerals.
The particles in meteorites are normally round, but the Aguas Zarcas meteorite has long elliptical grains. It may have been deformed due to a powerful collision with another object in space.

Seymchan

• Classification：stony-iron meteorite
• Year found：1967
• Place found：Magadan district, Russia

Seymchan is a stony-iron meteorite. You can see the difference between the stone and metal with the naked eye.
Observing it with an electron microscope allows us to see not just its shape, but the distribution of elements inside it. This stony-iron meteorite has different areas depending on the kind of metal it contains, for example magnesium or iron. There is a limit to how much sulfur and phosphorus the metal can contain, so where there is too much to be contained in the metal, these elements can be seen in the gaps between the metal sections.

Gibeon

• Classification：iron meteorite - octahedrite
• Year found：discovered before 1836
• Place found：Hardap Region/Namaqualand, Namibia

When the surface of iron meteorites is acid etched*, you can see the unique triangular and parallelogram-shaped banded pattern (Widmanstätten structure).
Normally, when the iron and nickel alloy in iron meteorites cools it produces a uniform composition. Because the meteorite cooled and hardened gradually over several million years, it is divided into areas with less nickel (kamacite) and areas with lots of nickel (taenite) which together form the Widmanstätten patterns. We can't artificially cool metal over millions of years, so these patterns are proof of iron meteorites. If the meteorite was made of pure iron, exposure to the elements would cause it to rust and disappear over time. The nickel content has allowed this iron meteorite to survive for 400 million years without rusting.

*A technique using acidic chemicals to dissolve and treat surfaces. The areas of iron meteorites with low nickel content melt more easily, so clear borders are created between areas with low and high nickel content.

Campo del Cielo

• Classification：iron meteorite - octahedrite
• Year found：discovered before 1576
• Place found：Chaco, Argentina

The Campo del Cielo is an iron meteorite that fell to Earth between 4000 and 5000 years ago, and it was discovered some time before 1576 in Argentina. The surface has not been acid etched*, so we cannot observe the patterns (Widmanstätten structures) unique to iron meteorites.

*A technique using acidic chemicals to dissolve and treat surfaces. The areas of iron meteorites with low nickel content melt more easily, so clear borders are created between areas with low and high nickel content.

NWA 5957

• Classification：howardite
• Year found：discovered in 1836
• Place found：Morocco

Howardites are meteorites that come from the surface of the asteroid Vesta, located in the asteroid belt between Mars and Jupiter. You can sometimes see the asteroid Vesta with the naked eye if you're in a place with no light pollution.
Quartz (silicon dioxide) crystals are visible in the center of the electron-microscope image. These meteorites have been completely melted and thrown out by another celestial object in the past — Earth is thought to have been formed in a similar way.

Libyan Desert Glass

• Classification：tektite
• Year found：discovered in 1932
• Place found：Egyptian/Libyan desert

Tektites are pieces of solid glass formed when terrestrial debris is melted and scattered by a meteorite's impact. The different materials in the Earth's surface get mixed together, but it is thought that because desert sand has very few impurities, the tektites formed there are clear and glassy.

Moldavite

• Classification：tektite
• Year found：reported at a scientific society in 1786
• Place found：Czechia

Tektites are pieces of solid glass formed when terrestrial debris is melted and scattered by a meteorite's impact. They are often black because they are a mixture of various materials from the Earth's surface. It is thought that the tektites formed in Czechia are clear and glassy because the ground there had very few impurities. On the electron-microscope image, you can see round protrusions on the surface.

Darwin Glass

• Classification：tektite
• Year found：discovered in 1972
• Place found：Tasmania, Australia

Tektites are pieces of solid glass formed when terrestrial debris is melted and scattered by a meteorite's impact. They are often black because they are a mixture of various materials from the Earth's surface.