0,75 غرام من نيزك مريخي NWA 15497، من نوع شيرجوتيت

Rarity and Value
Martian meteorite NWA 15497 is a rare basaltic shergottite originating from the volcanic crust of Mars. Ejected from the Martian surface by a powerful impact event, this meteorite traveled through space before ultimately reaching Earth. Its mineralogical composition, including shock-formed maskelynite, pigeonite, augite, and olivine, preserves direct evidence of Martian volcanic activity and planetary evolution. Meteorites of confirmed Martian origin are among the rarest extraterrestrial materials known, making specimens such as NWA 15497 exceptionally valuable to collectors, museums, and researchers studying the geological history of the Red Planet.

Discovery
The specimen was discovered in 2020 within the Sahara Desert of Northwest Africa, one of the world’s most productive meteorite recovery regions. The desert environment provides ideal preservation conditions, allowing rare extraterrestrial stones to remain identifiable over long periods of time. Detailed scientific analysis confirmed the Martian origin of NWA 15497 through its distinctive geochemical signatures, including Fe/Mn ratios and trace element enrichment characteristic of Martian basaltic shergottites. These properties connect the meteorite directly to magmatic processes on Mars and provide valuable information regarding the composition and thermal evolution of the Martian mantle and crust.

Preservation
This slice preserves a fine-grained basaltic matrix composed of low-calcium and high-calcium pyroxenes, olivine, chromite, ilmenite, and sulfide phases. The transformation of plagioclase into maskelynite records the immense shock pressures generated during the impact event responsible for launching the rock from Mars into space. Minor secondary alteration minerals indicate limited terrestrial weathering following its arrival on Earth. The meteorite retains exceptional internal integrity, preserving microscopic mineralogical structures essential for scientific examination and offering a remarkable physical connection to another planet within our Solar System.

Composition

Maskelynite (shock-transformed plagioclase), low-Ca pyroxene (pigeonite), high-Ca pyroxene (augite), olivine, and accessory phases within a fine-grained basaltic matrix containing chromite, ilmenite, sulfides and minor secondary alteration minerals.

Geochemistry

Plagioclase (An35–55, maskelynite), olivine (Fa25–40), low-Ca pyroxene (En50–60 Fs30–40 Wo5–10), high-Ca pyroxene (Wo30–45), with Fe/Mn ratios consistent with Martian origin, and trace elements showing enrichment in incompatible elements typical of Martian basaltic shergottites.