Types of Meteorites
Meteorites are solid debris that originates in outer space and survives through the passage of the earth’s atmosphere to reach its surface. Due to high friction, pressure, and chemical reaction with atmospheric gases, they heat up and radiate energy, forming fireballs that are called ‘shooting stars’. This debris typically originates from comets, asteroids, or meteoroids.
How many Types of Meteorites are There
There are three different types of meteorites based on the proportions of rock-forming minerals and metallic materials (iron-nickel) in their composition. All the types and their subtypes are mentioned below:
What Are the Different Types of Meteorites
Accounts for about 94% meteorites recovered on earth.
Formation: 75-90% rock-forming minerals like silicate, 10-25% of metallic elements (nickel-iron alloy), small amounts of iron sulfide
Characteristics: Stone-like appearance with small flecks of metal
About 86% of all meteorites found are chondrites
Formation: Being primitive, these can contain materials that predate the formation of the solar system and planets. Having never undergoing melting, these are often studied to learn about the origin of the universe.
Characteristics: Lots of chondrules (tiny metallic or mineral grains)visible on the surface
Subdivisions: Ordinary, carbonaceous, and enstatite chondrites
Examples: Ochansk in Russia, Allende in Mexico, Abee in Ontario museum
Younger than chondrites, these make up 8% of all meteorites recovered.
Formation: Formed due to igneous activity in planetary bodies that have distinct core and crust, like large asteroids, the moon, and mars.
Characteristics: Melting and re-crystallization eradicates ancient chondrules
Subdivisions: Howerdite, eucrite, and diogenite, together called HED meteorite
Examples: NWA 2698 in Africa, Millbillillie in Australia, Bilanga in Burkina Faso(West Africa)
Only 5% of meteorites found on earth are this type. These are most likely to survive atmospheric entry. Resistant to weathering, they remain intact for longer, with the largest meteorites recovered on earth being of this type.
Formation: 75-95% iron, cobalt about, 5-25% nickel, and trace amounts of troilite (iron sulfide). The iron in this meteorite is one of the earliest sources of iron available to humans to forge tools and weapons.
Characteristics: Typical crystal structure (Widmanstatten structure) can be seen when cut, polished and exposed to nitric acid
Formation: Low in nickel content(>5.8%), no Widmanstatten structure
Examples: Boguslavka meteorite
Formation: Low to average in nickel content (5-10%), visible Widmanstatten structure.
Examples: Sikhote-Alin meteorite in Russia
Formation: Very high nickel content (<18%), no Widmanstatten structure.
Examples: Hoba meteorite in Namibia
Accounts for about 2% of meteorites recovered on earth.
Formation: Composed of roughly equal parts of metal (iron-nickel alloy) and stone, originates from mixing of the metallic core and rocky magma within the asteroids. These are believed to have undergone melting and solidification multiple times that results in physical and chemical changes.
Characteristics: Smooth and sometimes glossy, embedded with silicates; often cut into gemstones (e.g. extraterrestrial peridot)
Formation: Solid metallic bodies of iron-nickel. These are believed to come from a combination of core and mantle materials of asteroids.
Characteristics: Centimeter-size greenish or olive crystals embedded in the body
Examples: Brenham in United States, Imilac in the Atacama desert in Chile
Formation: Originates when debris from different asteroid collisions are mixed and combined.
Characteristics: In contrast to pallasite, its crystals are smaller, pale silicate minerals.
Examples: Chinguetti in Africa, Vaca Muerta in the Atacama desert in Chile
Article was last reviewed on Tuesday, December 10, 2019