According to the International Mineralogical Association (IMA) it is considered a proper nickel-rich variety of the mineral native iron.

[3][4] The proportion iron:nickel is between 90%:10% and 95%:5%; small quantities of other elements, such as cobalt or carbon may also be present.

The mineral has a metallic luster, is gray and has no clear cleavage although its crystal structure is isometric-hexoctahedral.

At times kamacite can be found so closely intermixed with taenite that it is difficult to distinguish them visually, forming plessite.

[6] Kamacite has many unique physical properties including Thomson structures and extremely high density.

Kamacite is opaque, and its surface generally displays varying shades of gray streaking, or "quilting" patterns.

Thomson structures, usually referred to as Widmanstätten patterns, are textures often seen in meteorites that contain kamacite.

In 1804, William Thomson stumbled upon these structures when he noticed unexpected geometric patterns after cleaning a specimen with nitric acid (HNO3).

He published his observations in a French journal but due to the Napoleonic wars the English scientists, who were doing much of the meteorite research of the time, never discovered his work.

It was not until 1808, four years later, that the same etching patterns were discovered by Count Alois von Beck Widmanstätten who was heating iron meteorites when he noticed geometric patterns caused by the differing oxidation rates of kamacite and taenite.

Thomson structures or Widmanstätten patterns are created as the meteorite cools; at high temperatures both iron and nickel have face-centered lattices.

This is a non-conventional thermoremanent magnetization because it appears to be due to a chemical remanent process which is induced as taenite is cooled to kamacite.

[11] Kamacite is an isometric mineral with a body cubic centered unit cell.

The most notable trace elements in kamacite are gallium, germanium, cobalt, copper, and chromium.

[13] All of these trace elements are metallic and their appearance near the kamacite taenite border can give important clues to the environment the meteorite was formed in.

Ataxite refers to meteorites that do not show a grossly hexahedral or octahedral structure.

Both hexahedrites and octahedrite only appear when the meteorite breaks along crystal planes or when prepared to accentuate the Thomson structures therefore many are mistakenly called ataxites ar first.

[8][17] Kamacite is only stable at temperatures below 723 °C [8] or 600 °C (Stacey and Banerjee, 2012),[11] as that is where iron becomes cool enough to arrange in a body centered crystal structure.

[8] Metallographic and X-ray diffraction can be used on kamacite to determine the shock history of a meteorite.

[7] Shock causes a unique iron transformation structure that is able to be measured using metallographic and X-ray diffraction techniques.

[18] Kamacite is primarily associated with meteorites because it needs high temperatures, low pressures and few other more reactive elements like oxygen.

In the 1960s United States Geological Survey discovered kamacite in specimens gathered from around the site tying the mineral to meteorites.

[22] Kamacite primarily forms on meteorites but has been found on extraterrestrial bodies such as Mars.

Mesosiderites are very rare on Earth and its occurrence on Mars gives clues to the origin of its larger source rock.

[23] Due to the rareness and the generally dull appearance of kamacite it is not popular among private collectors.