The Eagle Station group (abbreviated PES - Pallasite Eagle Station) is a set of
pallasite meteorite specimen that don't fit into any of the other defined pallasite groups. In
meteorite classification
In meteoritics, a meteorite classification system attempts to group similar meteorites and allows scientists to communicate with a standardized terminology when discussing them. Meteorites are classified according to a variety of characteristics ...
five meteorites have to be found, so they can be defined as their own group.
Currently only five Eagle Station type meteorites have been found, which is just enough for a separate group.
Naming and history
The Eagle Station group is named after the
Eagle Station meteorite
The Eagle Station meteorite is a pallasite and type specimen of the Eagle Station group.
It was found in 1880 close to Eagle Station, Carroll County, Kentucky (United States). The first description was made by George F. Kunz in 1887.
Referen ...
, the type specimen of the group. It is in turned named after
Eagle Station,
Carroll County Kentucky
Kentucky ( , ), officially the Commonwealth of Kentucky, is a state in the Southeastern region of the United States and one of the states of the Upper South. It borders Illinois, Indiana, and Ohio to the north; West Virginia and Virginia ...
where it was found.
Description
The Eagle Station group has a composition similar to
Main group pallasites. Diagnostic differences are that the
olivine
The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickl ...
is richer in
iron
Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...
and
calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...
. The group also has a distinct
oxygen isotope
There are three known stable isotopes of oxygen (8O): , , and .
Radioactive isotopes ranging from to have also been characterized, all short-lived. The longest-lived radioisotope is with a half-life of , while the shortest-lived isotope is ...
signature.
The
meteoric iron
Meteoric iron, sometimes meteoritic iron, is a native metal and early-universe protoplanetary-disk remnant found in meteorites and made from the elements iron and nickel, mainly in the form of the mineral phases kamacite and taenite. Meteoric ir ...
is similar to the
IIF iron meteorites. This might indicate that Eagle station group and IIF formed close to each other in the
solar nebula.
Parent body
The
trace element
__NOTOC__
A trace element, also called minor element, is a chemical element whose concentration (or other measure of amount) is very low (a "trace amount"). They are classified into two groups: essential and non-essential. Essential trace elements ...
s in the phosphates of the Eagle Station group are distinct from other pallasites. Most pallasites are believed to be derived from the
core
Core or cores may refer to:
Science and technology
* Core (anatomy), everything except the appendages
* Core (manufacturing), used in casting and molding
* Core (optical fiber), the signal-carrying portion of an optical fiber
* Core, the centra ...
-
mantle boundary. Trace elements indicate that the Eagle Station group came from shallower depths of their parent body.
Notable specimen
Only five specimen have been found so far:
*
Cold Bay meteorite
Cold is the presence of low temperature, especially in the atmosphere. In common usage, cold is often a subjective perception. A lower bound to temperature is absolute zero, defined as 0.00K on the Kelvin scale, an absolute thermodynamic ...
*
Eagle Station meteorite
The Eagle Station meteorite is a pallasite and type specimen of the Eagle Station group.
It was found in 1880 close to Eagle Station, Carroll County, Kentucky (United States). The first description was made by George F. Kunz in 1887.
Referen ...
(type specimen)
*
Itzawisis meteorite
*
Karavannoe meteorite
*
Oued Bourdim 001
See also
*
Glossary of meteoritics
This is a glossary of terms used in meteoritics, the science of meteorites.
#
* 2 Pallas – an asteroid from the asteroid belt and one of the likely parent bodies of the CR meteorites.
* 4 Vesta – second-largest asteroid in the asteroid b ...
References
{{meteorites