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Allan Hills A77257 meteorite, Allan Hills, Victoria Land, Eastern Antarctica, Antarcticai
| Regional Level Types | |
|---|---|
| Allan Hills A77257 meteorite | Meteorite Fall Location |
| Allan Hills | Group of Hills |
| Victoria Land | Region |
| Eastern Antarctica | Region |
| Antarctica | Continent |
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Latitude & Longitude (WGS84):
76° 43' South , 159° 40' East
Latitude & Longitude (decimal):
Meteorite Class:
Meteoritical Society Class:
Köppen climate type:
Other/historical names associated with this locality:
ALHA77257; ALH 77257
Ureilite
Find 1997; 1996 g
The Ureilites are ultramafic achondrites that contain interstitial carbon as graphite or diamond. The ALHA77257 Ureilite contains small amounts of both graphite and diamond as well as several other interesting interstitial phases. ALHA77257's dominant lithology, however, is that of a fairly coarse-grained stone compositionally dominated by olivine (~80%) and accompanying pyroxene (~15%) grains. Undulose extinction in olivine, polysynthetic twinning in pyroxene, and microtextures in metal all provide clues for deciphering the impact history of this and other ureilites. Perhaps most significant is evidence from distorted graphite grains that the diamonds in this and other ureilites have indeed been produced primarily by shock impact.
Significant amounts of terrestrial weathering products (limonite, hydromagnesite, …) — usually concentrated in the interstitial phases — are noted by several observers.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsMineral List
7 valid minerals.
Meteorite/Rock Types Recorded
Note: data is currently VERY limited. Please bear with us while we work towards adding this information!
Select Rock List Type
Alphabetical List Tree DiagramDetailed Mineral List:
| ⓘ 'Clinopyroxene Subgroup' Description: Low Ca-Clinopyroxene |
| ⓘ Cohenite Formula: Fe3C |
| ⓘ Diamond Formula: C |
| ⓘ 'Fayalite-Forsterite Series' Description: variable compositions (Fa9-23, average Fa13); undulose extinction; many olivine grains with reduction at the rims References: |
| ⓘ Graphite Formula: C |
| ⓘ Hydromagnesite Formula: Mg5(CO3)4(OH)2 · 4H2O Description: Obvious and quite visible weatehring product |
| ⓘ 'Limonite' Description: a weathering product
|
| ⓘ Native Iron Formula: Fe |
| ⓘ Native Iron var. Kamacite Formula: (Fe,Ni) |
| ⓘ 'Nickel-iron' Description: Traces, partially or largely altered to limonite |
| ⓘ 'Pyroxene Group' Formula: ADSi2O6 Description: Fs. (mol%) 12, coarse polysynthetic twinning |
| ⓘ Taenite Formula: (Fe,Ni) |
| ⓘ Troilite Formula: FeS Description: Present only in traces References: |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 1 - Elements | |||
|---|---|---|---|
| ⓘ | Native Iron | 1.AE.05 | Fe |
| ⓘ | var. Kamacite | 1.AE.05 | (Fe,Ni) |
| ⓘ | Taenite | 1.AE.10 | (Fe,Ni) |
| ⓘ | Cohenite | 1.BA.05 | Fe3C |
| ⓘ | Graphite | 1.CB.05a | C |
| ⓘ | Diamond | 1.CB.10a | C |
| Group 2 - Sulphides and Sulfosalts | |||
| ⓘ | Troilite | 2.CC.10 | FeS |
| Group 5 - Nitrates and Carbonates | |||
| ⓘ | Hydromagnesite | 5.DA.05 | Mg5(CO3)4(OH)2 · 4H2O |
| Unclassified | |||
| ⓘ | 'Limonite' | - | |
| ⓘ | 'Clinopyroxene Subgroup' | - | |
| ⓘ | 'Fayalite-Forsterite Series' | - | |
| ⓘ | 'Pyroxene Group' | - | ADSi2O6 |
| ⓘ | 'Nickel-iron' | - | |
List of minerals for each chemical element
| H | Hydrogen | |
|---|---|---|
| H | ⓘ Hydromagnesite | Mg5(CO3)4(OH)2 · 4H2O |
| C | Carbon | |
| C | ⓘ Cohenite | Fe3C |
| C | ⓘ Diamond | C |
| C | ⓘ Graphite | C |
| C | ⓘ Hydromagnesite | Mg5(CO3)4(OH)2 · 4H2O |
| O | Oxygen | |
| O | ⓘ Hydromagnesite | Mg5(CO3)4(OH)2 · 4H2O |
| O | ⓘ Fayalite-Forsterite Series | |
| O | ⓘ Pyroxene Group | ADSi2O6 |
| Mg | Magnesium | |
| Mg | ⓘ Hydromagnesite | Mg5(CO3)4(OH)2 · 4H2O |
| Mg | ⓘ Fayalite-Forsterite Series | |
| Si | Silicon | |
| Si | ⓘ Fayalite-Forsterite Series | |
| Si | ⓘ Pyroxene Group | ADSi2O6 |
| S | Sulfur | |
| S | ⓘ Troilite | FeS |
| Fe | Iron | |
| Fe | ⓘ Cohenite | Fe3C |
| Fe | ⓘ Native Iron | Fe |
| Fe | ⓘ Native Iron var. Kamacite | (Fe,Ni) |
| Fe | ⓘ Taenite | (Fe,Ni) |
| Fe | ⓘ Troilite | FeS |
| Fe | ⓘ Fayalite-Forsterite Series | |
| Ni | Nickel | |
| Ni | ⓘ Native Iron var. Kamacite | (Fe,Ni) |
| Ni | ⓘ Taenite | (Fe,Ni) |
Other Regions, Features and Areas containing this locality
Antarctic MeteoritesGroup of Meteorite Fall Locations
Antarctic PlateTectonic Plate
- Ross Orogen
- South Victoria LandOrogenic Belt
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