0,79 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 regions of Mars. Formed between 150 and 600 million years ago, this meteorite preserves direct evidence of volcanic and impact-related processes that shaped the Martian crust. Its composition, including shock-transformed maskelynite, pyroxenes, and olivine, reflects the extreme conditions experienced during its ejection from Mars into space. Martian meteorites are among the rarest extraterrestrial materials known on Earth, making specimens such as NWA 15497 exceptionally valuable to collectors, museums, and planetary scientists studying the geological evolution of the Red Planet.

Discovery
This specimen was discovered in 2020 in the Sahara Desert of Northwest Africa, one of the world’s most important meteorite recovery regions. The dry desert environment preserves meteorites exceptionally well, allowing rare planetary material to remain identifiable for extended periods. Scientific analysis confirmed the Martian origin of NWA 15497 through diagnostic Fe/Mn ratios and trace element compositions characteristic of basaltic shergottites. These geochemical signatures provide important information regarding Martian volcanic activity, magmatic differentiation, and the chemical composition of the Martian mantle and crust.

Preservation
The slice preserves a fine-grained basaltic matrix composed of low-calcium and high-calcium pyroxenes, olivine, chromite, ilmenite, and sulfide minerals. The transformation of plagioclase into maskelynite records the immense shock pressures generated during the impact event responsible for launching the rock from Mars into interplanetary space. Minor secondary alteration minerals indicate only limited terrestrial weathering after arrival on Earth. The meteorite remains exceptionally well-preserved, retaining detailed mineralogical structures essential for scientific examination and providing a rare physical connection to the geological history of another planet.

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.