Description
A rare Hughes type of ureilite. From Egypt ! Sold in a box.
Hurghada 001 27º18.288’N, 33º 35.177’E
Al Bahr al Ahmar, Egypt
Find: 17 Nov 2022
Classification: Ureilite
History: A single 75.23 g stone was found by an anonymous individual 27.4km NE of Hurghada, Egypt, in 2022.
Physical characteristics: Stone has an irregular shape and is mottled brownish orange. The cut face shows a protogranular texture composed of mm-sized silicates whose grain boundaries are decorated with FeOH minerals.
Petrography: Description and classification (A. Love, App) Sample shows a protogranular texture composed of: up to 4mm subrounded olivine with reduced grain boundaries, low Ca and high Ca pyroxene some of which share 120º grain boundaries. Iron oxides minerals occur at boundaries between grains. Minerals grains are extensively fractured and pyroxenes show mechanical twinning and planar deformation lamellae. Additional minerals are: rare FeNi grains, rare feldspathic glass, troilite and schreibersite. Graphite is absent from this sample.
Geochemistry: (A. Love, App) Olivine (cores Fa11.6±0.3, Fe/Mn (molar)=19.6±0.8, Cr2O3 (wt%) =0.5±0.0, n=10; reduced rims Fa8.3±0.9, Fe/Mn=14.5±1.0, Cr2O3=0.5±0.0 n=10, CaO=0.24±0.0, n=10); low Ca-pyroxene (Fs11.2±0.2Wo4.1±0.0, Fe/Mn=13.1±0.5 n=10); Ca-pyroxene (Fs6.1±0.1Wo36.2±0.2, Fe/Mn=10.0±0.4 n=10).
Classification: Primitive achondrite (ureilite U-S4 moderate weathering). Based on mineralogy, textures and mineral compositions (e.g., elevated CaO and Cr2O3 in olivine), sample is a ureilite. Absence of graphite, presence of likely melt inclusions, presence of high-Ca pyroxene, and mineral Mg#s are properties similar to the Hughes type ureilites.
Specimens: The main mass is held by an anonymous collector. A polished thin section and an end cut weighing 16.27 g are on deposit at App.
