EucriteMost common type of achondrite meteorite and a member of the HED group. Eucrites are basalts composed primarily of pigeonite and anorthite (An60-98). Eucrites have been placed into three subgroups based on mineralogical and chemical differences. • Non-cumulate eucrites represent the upper crust that solidified on a magma ocean after Click on Term to Read More
Monomict, noncumulate
(Main Group–Nuevo Laredo trend)
purchased 2001
no coordinates recorded
Multiple stones and fragments totaling ~823 g were purchased in Morocco by an association of
meteoriteWork in progress. A solid natural object reaching a planet’s surface from interplanetary space. Solid portion of a meteoroid that survives its fall to Earth, or some other body. Meteorites are classified as stony meteorites, iron meteorites, and stony-iron meteorites. These groups are further divided according to their mineralogy and Click on Term to Read More collectors known by the name of Trinity Meteorites. The exterior of this
eucriteMost common type of achondrite meteorite and a member of the HED group. Eucrites are basalts composed primarily of pigeonite and anorthite (An60-98). Eucrites have been placed into three subgroups based on mineralogical and chemical differences. • Non-cumulate eucrites represent the upper crust that solidified on a magma ocean after Click on Term to Read More is covered with black
fusion crustMelted exterior of a meteorite that forms when it passes through Earth’s atmosphere. Friction with the air will raise a meteorite’s surface temperature upwards of 4800 K (8180 °F) and will melt (ablate) the surface minerals and flow backwards over the surface as shown in the Lafayette meteorite photograph below. Click on Term to Read More, and the interior is light tan in color with an ultra fine-grained texture, with
mineralInorganic substance that is (1) naturally occurring (but does not have a biologic or man-made origin) and formed by physical (not biological) forces with a (2) defined chemical composition of limited variation, has a (3) distinctive set of of physical properties including being a solid, and has a (4) homogeneous Click on Term to Read More grains of
pyroxeneA class of silicate (SiO3) minerals that form a solid solution between iron and magnesium and can contain up to 50% calcium. Pyroxenes are important rock forming minerals and critical to understanding igneous processes. For more detailed information, please read the Pyroxene Group article found in the Meteoritics & Classification category. Click on Term to Read More and
plagioclaseAlso referred to as the plagioclase feldspar series. Plagioclase is a common rock-forming series of feldspar minerals containing a continuous solid solution of calcium and sodium: (Na1-x,Cax)(Alx+1,Si1-x)Si2O8 where x = 0 to 1. The Ca-rich end-member is called anorthite (pure anorthite has formula: CaAl2Si2O8) and the Na-rich end-member is albite Click on Term to Read More measuring tens of microns in size.
Northwest Africa 999 is a brecciated eucrite, possibly monomict, composed of very fine-grained basaltic material, which represent both the host and clasts in the meteorite. Widely scattered shock-melt veins of glass are present. The very fine-grained texture of this eucrite is consistent with rapid cooling from an extruded igneous melt. Although it exhibits the typical thermal
metamorphicRocks that have recrystallized in a solid state due to changes in temperature, pressure, and chemical environment. Click on Term to Read More features characteristic of other equilibrated
eucritesMost common type of achondrite meteorite and a member of the HED group. Eucrites are basalts composed primarily of pigeonite and anorthite (An60-98). Eucrites have been placed into three subgroups based on mineralogical and chemical differences. • Non-cumulate eucrites represent the upper crust that solidified on a magma ocean after Click on Term to Read More, it does not exhibit a high degree of textural equilibration (Warren and Choe, 2009). From a preliminary analysis performed by UCLA, NWA 999 was determined to be an extremely fine-grained eucrite that is slightly Fe-rich and REE-rich. The bulk composition of this eucrite plots with the Main Group–Nuevo Laredo trend. Black mineral grains (possibly
chromiteBrownish-black oxide of chromium and iron (Cr-Fe oxide), Cr2FeO4, found in many meteorite groups. Click on Term to Read More) are interspersed throughout the
matrixFine grained primary and silicate-rich material in chondrites that surrounds chondrules, refractory inclusions (like CAIs), breccia clasts and other constituents. Click on Term to Read More, and a rare FeNi-metal grain is present in the specimen shown above. This eucrite experienced low- to moderate-shock and is cross-cut by thin, dark-gray, shock-melt veins. The specimen of NWA 999 shown above is a 2.44 g slice.
