Antarctic Search for Meteorites (ANSMET) Search this
Weight:
0.365 g
Place:
Antarctica
Collection Date:
1991
Notes:
# NASA data for TIL 91708 Weathering: B/C Fracturing: A Pairing: TIL 91700 Fa: 25 mol % Fs: 19-24 mol % NTL: 58.8 ± 0.2 krad
Between 25% and 95% of the exteriors of these meteorites are covered with thin black fusion crust. The interiors show dark gray to black matrix with large oxidation haloes and heavy oxidation in places. Numerous inclusions range in size from <1 mm to 2 mm, many larger clasts were noted, one in particular is 0.9 x 0.5 cm in 91704.
The textures, mineral compositions, and degree of weathering shown by these sections are so similar that the meteorites can confidently be paired. The sections show a close-packed aggregate of chondrules, chondrule fragments, and occasional clasts, with minor subequal amounts of nickel-iron and troilite. Minor weathering is indicated by brown limonitic staining throughout the sections. Microprobe analyses show fairly uniform olivine compositions (Fa₂₃₋₂₅) and variable pyroxene compositions (Fs₁₅₋₂₅). The meteorites are classified as L4 chondrites, although the nickel-iron content appears to be higher than the normal for L-group chondrites. Additional members of this pairing group are: TIL91705, 91718, and 91720. Optical examination shows that TIL91701, 91709, and 91712 are also paired with these meteorites.
