Oriented meteorite
An oriented meteorite is one that kept the same face forward during its fall, giving it a cone or shield shape.
Most meteoroids tumble as they fall, so they are heated evenly on all sides. A few, however, settle into a stable position, like a dart flying point first. These keep one face pointing forward for much of their flight. The front is worn into a rounded cone or shield shape, and the result is called an oriented meteorite.
Oriented meteorites are prized by scientists and collectors because their surfaces tell a clear story. Regmaglypts on the front often spread outward from the tip, while the back may have a thicker, rougher crust with bubbles where melt collected. Flow lines may stream from front to back. The great Willamette iron, found in Oregon in 1902 and weighing about 15.5 tonnes, is a famous example of a cone-shaped oriented meteorite, though its surface is also deeply pitted by long weathering on the ground.
To recognise an oriented stone, look for a smooth domed or conical front, features that radiate from its centre, and a flatter back with a different texture. Small oriented specimens are a delight to examine with a hand lens.
Related terms
Level: Explorer Ages 10 and up