Types of Meteorites

Meteorites can be subdivided into three groupings on the basis of how much silicate material compared to iron they contain: (1) Stones; (2) Stony-Irons and (3) Irons. Stones are by far the most abundant meteorite type and are further subdivided into chondrites and achondrites, essentially on the basis of whether or not they contain mm-sized spherical objects known as chondrules. 

Cheljabinsk_meteorite_fragment

The Chelyabinsk meteorite is an example of a “Stone” in that it contains a significant amount of silicate material and only a small percentage of Fe, Ni metal. Image: Wikipedia

NHM_-_Pallasit_Fukang

The photo above shows a thin slice of the Fukang pallasite an example of a “Stony-Iron” meteorite. The transclucent crystals are olivine, a silicate mineral which is surrounded by opaque Fe, Ni metal. Stoney-Irons are roughly a 50:50 mixture of silicate and metal. Image: Wikipedia

The_Hoba_Meteorite_near_Grootfontein

The Hoba iron meteorite is an example of an “Iron” being composed predominately of Fe, Ni metal. Image: Wikipedia

Camera: DCS420D Serial #: 420-8125 Width: 1524 Height: 1012 Date: 25/2/00 Time: 13:16:04 Counter: [67] ISO: 100 Aperture: F-- Shutter: 200 Lens (mm): ?? Exposure: M Program: LA Exp Comp: 0.0 Meter area: Spot Flash sync: Norm Drive mode: H Focus mode: M Focus area: Spot Distance: ??

The circular features in this image are known as chondrules and are thought to have formed as molten droplets in space early in solar system history. Meteorites that contain chondrules are known as chondrites. The diameter of the largest chondrule in this image is about 0.3 mm.

Allan_Hills_81005,_lunar_meteorite

ALH 81005 is a lunar meteorite that was discovered in Antarctica. It doesn’t contain chondrules and hence is an example of an achondrite.