Identifying a Meteorite Martian

Meteorites are solid pieces of natural space debris that do not completely disintegrate during their descent through the Earth’s atmosphere. Research suggests that most meteorites come from fragments of asteroids in solar orbits between Mars and Jupiter, but some meteorites also originate from the Moon and Mars. You can find the following websites which provide excellent information about Martian meteorites:

85% of meteorites falling on Earth are chondrites, containing small, partly glassy spheres called chondrules, which are composed mostly of silicate minerals. Finding these small silicate balls in a rock suggests it is a chondrite. Other meteorites lacking condrules are called achondrites, and a subset of those are commonly referred to as planetary meteorites. During the descent through the Earth’s atomospher, the molten surface layer solidifies into a thin black crust, smooth and sometimes brilliant, termed “fusion crust”. This crust is black if the meteorite is collected shortly after its fall. Most meteorites are found long afterwards, and they may turn brown or even disappear due to weathering with time. Some depressions named “regmaglypts” can also be noted due to its passage through the Earth’s astmosphere. Most meteorites contain a substantial quantity of iron-nickel metal and have a density above the average density of terrestrial rocks. The relatively rare iron meteorites and also the pallasites presumably represent the disaggregated cores of former planetary bodies.

Two stones weighing 95.3 and 9.4 g were found and subsequently purchased in Zagora in 2016. Don Cline and John Sinclair acquired the samples from a meteorite prospector at the Tucson Gem and Mineral Show in February 2016. Sample is ovoid in shape and contain small patches of vesicular, black impact melt material (some of which contains embedded sand grains). The exterior surface is dark green and displays an igneous texture.

They have a narrow range of oxygen isotopic compostitions. A single chemical element may be found under several isotopes depending on its number of neutrons. Natural occuring oxygen is composed of three stable isotopes which are 18O with eighteen neutrons, 17O with seventeen neutrons, and 16O neutrons. Scientists found that the SNC meteorites (Shergottite, Nakhlite and Chassignite, three Martian meteorite groups) are algined together on the diagram showing the ratio of amounts of 18O and 17O.

Oxygen Isotopic Composition Diagram


They are classified as Martian meteorites based on the Fe/Mn ratio within pyroxenes, the An-Ab-Or compostition of maskelynite, and Nb/Ta and Zr/Hf ratios, and their d17O and d18O compostion falls within the cluster of data for Martian meteorites.