Sample No.:	LAP 04757; LAP 04773
Location:	LaPaz Ice Field
Field No.:	17603; 17035
Dimensions (cm):	2.5x2.0x1.0; 2.25x1.25x1.5
Weight (g):	12.8; 8.298
Meteorite Type:	Chondrite Ungrouped

Macroscopic Description: Kathleen McBride
Exteriors of these meteorites have dull brown/black fusion crust with oxidation haloes. The interiors reveal a rusty brown/black matrix with high metal content.

Thin Section (,2) Description: Tim McCoy and Valerie Reynolds
These meteorites are so similar that a single description suffices. The sections consist of abundant chondrules set in a metal- and sulfide-bearing, weathered matrix. Shock effects are present, including metal-sulfide melting at grain boundaries. Olivine is homogeneous at Fa₁₃ and pyroxene exhibits a small range at Fs_13-16. Links to the acapulcoites or low-FeO chondrites (Russell et al., 1998, MAPS 33, 853-856) should be considered, although LAP 04773/04757 are less metamorphosed than the former and more magnesian than is typical for the latter.

Oxygen Isotope Analysis: D. Rumble
Analysis for two subsamples of LAP 04757 give: A) δ¹⁸O = +3.67, δ¹⁷O = +2.68, and Δ¹⁷O = 0.746; B) δ¹⁸O = +3.75, δ¹⁷O = +2.94, and Δ¹⁷O = 0.97. These values plot above the terrestrial fractionation line, suggesting an unusual low FeO ordinary chondrite such as Burnwell.

Thin Section Images

Cross-Polarized Light LAP 04757	Plane-Polarized Light LAP 04757	Reflected Light LAP 04757

Cross-Polarized Light LAP 04773	Plane-Polarized Light LAP 04773	Reflected Light LAP 04773

Lab Images