Amphoterite
Encyclopedia
Amphoterite is an obsolete term used to describe chondritic
meteorite
s that are now classified as LL
(Low Iron
and Low total metal
content) types. Most of the iron
in these types of meteorites is present as ironoxide in the mineral
s (e.g. olivine
) rather than as free metal, as it is found in most other meteorites. Free metallic iron amounts to between 0.3% and 3.0% of the meteorite, and with a total iron content of 20% give or take a couple of percentage points. There will be a number after the LL in a meteorites classification type, e.g. LL3, LL5, LL6. (Types range from 3 to 7) The number indicates the amount of alteration suffered by the chondrule
s in the meteorite. A chondrule is a small mineral ball generally 0.1 mm to 4 mm in diameter. An LL3 type is pristine with perfectly discernible chondrules, an LL7 type has been melt
ed or altered by pressure
or other force to almost completely obliterate the round chondrules.
Chondrite
Chondrites are stony meteorites that have not been modified due to melting or differentiation of the parent body. They formed when various types of dust and small grains that were present in the early solar system accreted to form primitive asteroids...
meteorite
Meteorite
A meteorite is a natural object originating in outer space that survives impact with the Earth's surface. Meteorites can be big or small. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids...
s that are now classified as LL
LL chondrite
The LL chondrites are a class of stony meteorites, the least abundant group of the ordinary chondrites, accounting for about 10–11% of observed ordinary-chondrite falls and 8–9% of all meteorite falls ....
(Low Iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
and Low total metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
content) types. Most of the iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
in these types of meteorites is present as ironoxide in the mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
s (e.g. olivine
Olivine
The mineral olivine is a magnesium iron silicate with the formula 2SiO4. It is a common mineral in the Earth's subsurface but weathers quickly on the surface....
) rather than as free metal, as it is found in most other meteorites. Free metallic iron amounts to between 0.3% and 3.0% of the meteorite, and with a total iron content of 20% give or take a couple of percentage points. There will be a number after the LL in a meteorites classification type, e.g. LL3, LL5, LL6. (Types range from 3 to 7) The number indicates the amount of alteration suffered by the chondrule
Chondrule
Chondrules are round grains found in chondrites. Chondrules form as molten or partially molten droplets in space before being accreted to their parent asteroids...
s in the meteorite. A chondrule is a small mineral ball generally 0.1 mm to 4 mm in diameter. An LL3 type is pristine with perfectly discernible chondrules, an LL7 type has been melt
Melt
Melt can refer to:* Melting, in physics, the process of heating a solid substance to a liquid*Melt , the semi-liquid material used in steelmaking and glassblowing*Melt inclusions, a feature of igneous rock...
ed or altered by pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
or other force to almost completely obliterate the round chondrules.