Meteorite Glossary - Letter O

Octahedrite:

A broad class of iron meteorites which is characterized by the presence of both Taenite and Kamacite nickel iron minerals in the crystal structure of the meteorite. Octahedrite meteorites will normally show a Widmanstatten pattern when sliced polished and etched. Size of the crystals determines the sub-class from coarsest to fine octahedrite.

Olivine:

A magnesium-iron silicate mineral commonly found in meteorites. It occurs as microscopic crystal grains in chondrites and as large often well formed crystals in pallasites.

Oriented:

A meteorite which makes it passage through the atmosphere in a stable orientation toward the ground may receive characteristic ablation features from being melted mostly on one surface. Among these features are a cone shaped or a rounded front surface, radial lines of melting in the front surface, and a rolled over lip of melted material which has cooled around the circumference of the back side. Sometimes these features maybe exaggerated to actual splattering or bubbling of material onto the back side as well as deep radial furrows in the front surface. Oriented meteorites should be recognized as distinct from meteorite fragments which may show ablation on a surface that is similar in appearance but does not indicate that the meteorite as a whole is oriented.