Difference Between Holes, Cavities, and Vesicles in Meteorites

When people think they have found a meteorite, much more often than not, what they found is actually a terrestrial rock, often referred to as a meteorwrong. These rocks come in all shapes, sizes, colors and textures, and sometimes include holes. In posting these specimens for review, they may be told that “meteorites do not have holes”. Though generally true, this statement misleading because a simple internet search will uncover images of actual meteorites with holes. This article is written to clarify this issue.

Though our definitions for holes and cavities differ somewhat from the dictionary definition, they are better descriptors than what is normally used to describe meteorites.

Holes can be caused by ablation or various types of terrestrial weathering and generally describe a void that extends all the way through a specimen.

Cavities can also be caused by ablation and in that case are called regmaglypts, or by the weathering of softer or more degradable material within the meteorites such as troilite in iron meteorites.

 

Vesicles are caused due due trapped gases expanding within the molten material/melt at its time of formation and are rarely bigger than a few millimeters, though in extremely rare cases one or two larger vesicles can by be larger. Vesicles inside meteorites do not occur due to its voyage through our atmosphere, though bubbles/vesicles can form on the outside crust during entry.

Ibitira eucrite meteorite with vesicles.
Tissint Martian shergottite with vesicles in shock melt veins. Image Credit: Mendy Ouzillou

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