Sample Petrographic Description
Sample Number | QUE 99001 |
Newsletter | 23,2 |
Location | Queen Alexandra Range |
Field Number | 11635 |
Dimensions (cm) | 22 x 24 x 14.5 |
Weight (g) | 22000.00 |
Original Classification | Iron |
Macroscopic Description - Tim McCoy, Linda Welzenbach, Kathleen McBride | |
The mass is an irregular triangle in outline, and wedge-like in cross-section, 22 x 24 cm, and 14.5 at its widest tapering to 9.5 cm. Found partially within the ice at the time of recovery, the surface is marked by a definite line of color and texture change corresponding to the area below the ice. Almost half the meteorite, a short leg of the triangle, was below the ice. This area is light reddish-brown to orange, red and greenish oxidation colors. Luster is matte, and the surface expression is undulatory and mildly micropitted. In contrast, the above ice half is dark metallic reddish-brown, heavily sculpted and micropitted. Millimeter-sized whitish specks are evenly distributed over the same. Prominent features include a 4cm vug with minor flaking, surrounded by a whitish evaporative ring, and a 3 cm deep, 2 cm wide and 7 cm long gash-like vug, both in the below ice portion. A complete hole goes through one corner of the above ice section. | |
Thin Section Description - Tim McCoy, Linda Welzenbach | |
The main mass (,0) was cut twice. The first cut remove a 7.5 cm thick end piece cutting across the ice line and intersecting the long gash-like vug. The second cut removed a parallel 2.7 cm thick slice with a surface area of 11 x 20 cm. The cut face of the end piece and one face of the slice were polished, etched and examined in a binocular microscope for this description. The overall structure is between a coarse (Og) and coarsest (Ogg) octahedrite with short (L/W~5) kamacite bands with bandwidths of 3-5 mm. There are coarser kamacite regions often 2-3 cm in diameter, but reaching up to 5 cm. Subgrain boundaries are common in the kamacite, as are Neumann bands. Terrestrial weathering has penetrated along many of the grain boundaries and produced cracks, even in the interior of the meteorite. The meteorite has a prominent heat altered zone extending 1-5 mm into the interior and in some places, particularly on one side of the slice, preserves the original fusion crust. The 7 cm long gash-like vug opens up through a small crevice into a 1.5 cm diameter tube extending back another 8-10 cm. This 1.5 cm diameter tube was filled with sulfide, which remains at the opposite end of the tube and is exposed on the opposite face of the meteorite. The large slice has an exposed troilite nodule, partially ablated during atmospheric passage, measuring 2 by 2.5 cm. The troilite is polycrystalline, with domains approaching 7 mm. Graphite is rare or absent and the troilite appears only incompletely rimmed by schreibersite. No silicates were observed. The appearance is similar in many respects to some of the coarsest IAB irons, particularly Osseo (Buchwald, 1975). However, the troilite inclusion does not appear to contain graphite or the typical inclusion rimming sequence (graphite, cohenite, schreibersite, swathing kamacite) seen in many IAB irons. The possibility exists that this meteorite, like many Antarctic irons, is ungrouped. |
Antarctic Meteorite Images for Sample QUE 99001 | ||||
Lab Photo(s) : | ||||