Olivine–High-Ca clinopyroxene, (Ca,Mg,Fe)SiO3, that occurs in many igneous rocks, particularly those of basaltic composition. In order to be considered augite, the clinopyroxene must contain 20 to 45 mol % of calcium (Wo20 - 45). An important and unique Martian meteorite is NWA 8159, that has been classified as an augite Click on Term to Read More
28° 46.66′ N., 12° 20.13′ E. A single stone weighing 136 g was found in the Libyan Sahara, and was classified at the Institut für Planetologie in Münster as a pyroxene-rich (A class of silicate (SiO3) minerals that form a solid solution between iron and magnesium and can contain up to 50% calcium. Pyroxenes are important rock forming minerals and critical to understanding igneous processes. For more detailed information, please read the Pyroxene Group article found in the Meteoritics & Classification Click on Term to Read More/pyroxene + Group of silicate minerals, (Mg,Fe)2SiO4, with the compositional endpoints of forsterite (Mg2SiO4) and fayalite (Fe2SiO4). Olivine is commonly found in all chondrites within both the matrix and chondrules, achondrites including most primitive achondrites and some evolved achondrites, in pallasites as large yellow-green crystals (brown when terrestrialized), in the silicate portion Click on Term to Read More = 65 vol%), unbrecciated ureilite. It has been weathered to grade 3 and exhibits only weak shock features (S3), as reflected in planar fractures and undulatory In astronomy, the dimming of starlight as it passes through the interstellar medium. Dust scatters some of the light, causing the total intensity of the light to diminish. It is important to take this effect into account when measuring the apparent brightness of stars. The dark bands running across portions Click on Term to Read More in the silicates. However, the presence of possible shock-produced diamonds within carbon-rich areas suggests that some shock features might have been erased during annealing.
FRO 90054/90228/90233/93008 (aug-bearing clasts)
DaG 999 (single aug-bearing A mineral or rock fragment embedded in another rock. Click on Term to Read More)
Y-74123 (aug within melt veins)
Y-790981 (aug within melt veins)
NWA 3222 (37–41 vol% augite)
Ramlat as Sahmah 530 (aug-bearing)
NWA 11900 (aug-bearing) In an attempt to identify possible common ejection events among the ureilites, Beard and Swindle (2017) conducted a comparative study of 39 different samples utilizing three parameters: CRE age, Fo content in olivine (Mg#), and Δ17O value. They resolved ten potential clusters, several of which show concordance in their CRE age and Mg# but not in Δ17O value (heterogeneous), and three that are concordant in all three parameters (homogeneous). The youngest heterogeneous cluster reflects an ejection event that occurred 0.7 (±0.1) m.y. ago and comprises HaH 064 and Acfer 277. A cohesive model for the petrogenesis of the ureilites was presented by Goodrich et al., LPSC XXXIII, #1379 (2002), which was followed by important modifications in subsequent publications (Goodrich et al., 2007), some details of which can be found on the Kenna and Almahata Sitta pages. The specimen of HaH 064 shown in the photos above and below is a 4.23 g partial slice that was sectioned from the portion curated at the Museum für Naturkunde, Humboldt University, Berlin.
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Photography courtesy of Stephan Kambach