Stony iron meteorites are thought to have originated at the mantle of differentiated asteroids, where the metallic core meets silicated rocks from the crust. They are a transition between two remarkably different lithologies. After they combined and formed, they were shattered into space as the result of another cosmic impact. They remained in space, usually orbiting the Sun until they fell upon the Earth. The proportion of silicates to metal is about 50% for each. However, it is not uncommon to sometimes see stony-iron meteorites with a higher content of one than the other. There are two types of stony-iron meteorites: pallasites and mesosiderites.
Pallasites
Pallasites are considered by many to be the most beautiful type of meteorite. They originated at the core-mantle boundary of differentiated asteroids, where the metallic core meets lighter silicated rocks (olivines). Then, they were shattered into space as the result of another meteorite impact, where they remained until they fell upon the Earth. There are 3 sub classes. Main group (90% of pallasites), Ungrouped (6%) and Eagle Station group (4%). Pallasites consist of a metallic matrix with high quantity of olivine inclusions. Due to their aesthetics when cut, they are often used in jewelry. They also make attractive show-pieces when cut in half or sliced.
Mesosiderites
Mesosiderites are thought to have originated at the core-mantle boundary of a differentiated asteroid, where the metallic core meets the lighter rocks. They were then shattered into space as the result of another meteorite impact, where they remained until they fell upon Earth. Mesosiderites have similar parts of metal to rock. It is a chaotic mixture, some parts being rock with metal inclusions and others being metal with rock inclusions. There are 3 sub classes (A, B and C) which are based on textural and mineralogical differences. Asteroid 16 Psyche is considered the main candidate as the parent body for mesosiderites. It orbits the Sun between Mars and Jupiter in the asteroid belt.
Additional resources
Click on the link to learn about impactites: Information About Impactites.
For a detailed guide on identifying meteorites visit: How to Identify a Meteorite.
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