Transcript METEORITES - City University of New York

METEORITES
METEORITE COMPOSITION
93% Stony Meteorites: Fe, Mg, Si, O compounds as oxides and silicates
6% Iron Meteorites: Fe-Ni alloys
1% Chondrites:
METEORITE COMPOSITIONS AND EARTH ANALOGUES
Type
Relative
Composition
Rock Type
EarthLayer
Abundance,%
Stony Meteorites
94
Chondrites
86
Ordinary
82 Fe, Mg
Silicates
Carbonaceous
intrusive igneous and Mantle
meta-igneous
4 Carbon, gases
Crust
hydrated silicates,
up to 20% water
Achondrites
Stony Iron
8 Fe, Mg Silicates
1 Silicates and Fe alloys
Igneous basalt lava
ocean crust
primitive
planet
Iron
5 Fe, Fe-Ni alloys
Core
Iron Meteorite
Elemental Abundances of top
100km of Earth
Meteorite with carbonate
modules
CHONDRITE
Meteorite with micro-fossils from
Mars
Most meteorites fall into one of four categories..
•"Iron meteorites", also called "irons", are usually just one big blob
of iron-nickel (Fe-Ni) metal, as if it came from a industrial refinery
without shaping. The alloy ranges from 5% to 62% nickel from
meteorite to meteorite, with an average of 10% nickel. While most
"irons" are pure or nearly pure metal, the technical definition of an
"iron" includes metal meteorites with up to 30% mineral inclusions
such as sulfides, metal oxides and silicates. The irons represent the
cores of former planetoids.
•"Stony irons" consist of mixtures of Fe-Ni metal of between
30% and 70% along with mixtures of various silicates and other
minerals. The Fe-Ni metal can be present as chunks, pebbles
and granules. Stony irons resemble the outer cores or mantles
of planetoids or else a mix of materials due to a collision.
•"Achondrites" are silicate rich meteorites apparently formed by
crustal igneous (i.e., molten or volcanic) activity in their parent
bodies, and consist of a broad range of minerals. Achondrites are
the result of gravitational differentiation in relatively large bodies
by melting and gravitational separation of mineral phases, and
most resemble the Earth's crust. Different types of achondrites
average between 0 and 4% free Fe-Ni granules.
•"Chondrites". Chondrites are named after the tiny pellets of rock
called "chondrules" embedded in them, a result of a kind of
chemical fractionation.
There are different subcategories of chondrites.