Sample Petrographic Description
Sample Number | ALH 78188 |
Newsletter | 4,1 |
Location | Allan Hills |
Field Number | 40 |
Dimensions (cm) | |
Weight (g) | 0.87 |
Original Classification | L3 Chondrite |
Updated Classification | L3.5 Chondrite |
Pairing | ALH 77011; ALH 77015; ALH 77031; ALH 77033; ALH 77034; ALH 77036; ALH 77043; ALH 77047; ALH 77049; ALH 77050; ALH 77052; ALH 77115; ALH 77140; ALH 77160; ALH 77163; ALH 77164; ALH 77165; ALH 77166; ALH 77167; ALH 77170; ALH 77175; ALH 77178; ALH 77185; ALH 77211; ALH 77214; ALH 77241; ALH 77244; ALH 77249; ALH 77260; ALH 77303; ALH 78013; ALH 78015; ALH 78017; ALH 78037; ALH 78038; ALH 78041; ALH 78162; ALH 78170; ALH 78176; ALH 78180; ALH 78186; ALH 78188; ALH 78235; ALH 78236; ALH 78238; ALH 78239; ALH 78243; ALH 79001; ALH 79045; ALH 80133; ALH 81025; ALH 81030; ALH 81031; ALH 81032; ALH 81053; ALH 81060; ALH 81061; ALH 81065; ALH 81066; ALH 81069; ALH 81085; ALH 81087; ALH 81121; ALH 81145; ALH 81156; ALH 81162; ALH 81190; ALH 81191; ALH 81214; ALH 81229; ALH 81243; ALH 81259; ALH 81272; ALH 81280; ALH 81292; ALH 81299; ALH 83038; ALH 85155; |
Mineral Composition (%Fa & %Fs) | |
Fayalite (mol%): 1-34;Ferrosilite (mol%): 5-29 | |
Weathering | |
C | |
Fracturing | |
B | |
Macroscopic Description - | |
No fusion crust remains on this reddish-brown totally weathered sample. | |
Thin Section Description - Brian Mason | |
The meteorite consists of a close-packed aggregate of chondrules, 0.3-1.2 mm across, with a relatively small amount of matrix. Porphyritic olivine chondrule contain intergranular glass, some of which is transparent brown but much is turbid from partial devitrification. Other chondrules consist of granular olivine and polysynthetically-twinned low-Ca clinopyroxene. Many chondrules have dark rims consisting largely of troilite. A little nickel-iron is present. Weathering is extensive, with veins and patches of brown limonite throughout the section. Microprobe analyses show variable composition for both olivine and pyroxene; olivine, Fa1-34, average Fa15; pyroxene, Fs5-29, average Fs17. The variability in olivine and pyroxene composition indicates type 3, and the low metal content suggest L group, so the meteorite is tentatively classified an L3 chondrite. | |
Reclassification Notes (AMN OUTSIDE) | |
Classification updated in Meteoritical Bulletin 76. |
Antarctic Meteorite Images for Sample ALH 78188 | ||||
Thin Section Photo(s) : | ||||