131.8g Diogenite I HED Achondrite Meteorite from Asteroid 4 Vesta
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- $ 1,300.00
The HED meteorites are so named for the three types of meteorites that comprise the group; Howardite, Eucrite and Diogenite. The Eucrite and Diogenite are meteorites with distinct chemistries, while the Howardite is a mix of the eucritic and diogenitic material. The HEDs are differentiated achondritic meteorites, thought to originate from the large differentiated asteroid 4 Vesta. Vesta is one of the only asteroids visible with the naked eye and low powered telescopes.
The Vesta parent body origin for the HED clan of meteorites is considered to have been conclusively established for many years. However, the late Dr. John Wasson, a planetary science researcher from UCLA had long held that the HED meteorite clan originated from another unknown Vesta-like asteroid that was blown apart long ago. This is because we also find a class of iron meteorites with nearly identical oxygen isotopes as the HED clan. This along with other research lead Dr. Wasson to conclude the HED clan of meteorites come from another differentiated V-type asteroid that was in a cataclysmic collision liberating part or all of its metal core along with the HED meteorites.
However, this hypothesis does not necessarily rule out the possibility that a "reaccreted" Vesta and the smaller V-type asteroids collectively known as Vestoids along with the HED meteorites and the isotopically paired irons were all once part of a much larger dwarf planet prior to a massive collision with another large body. While most researchers consider the case mostly closed on this debate, the paradox of isotopically paired core metal raised by Dr. Wasson's hypothesis has not been resolved. This leaves some to speculate that perhaps we still have more to learn about this fascinating clan of achondrite meteorites and even Vesta itself. Diogenite have distinct mineralogies, the Howardite is a breccia of the Eucrite and Diogenite.
Northwest Africa 12927
Status: Official
| Basic information |
Name: Northwest Africa 12927 This is an OFFICIAL meteorite name. Abbreviation: NWA 12927 Observed fall: No Year found: 2016 Country: (Northwest Africa) Mass: 3.8 kg |
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| Classification history: |
Meteoritical Bulletin, MB 108 (2020): Diogenite |
| Comments: | Approved 21 Nov 2019 |
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Writeup
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Writeup from MB 108: Northwest Africa 12927 (NWA 12927) (Northwest Africa) Purchased: 2016 Classification: HED achondrite (Diogenite) History: Purchased Nov 2016 by Dustin Dickens in Mauritania from anonymous dealer. Physical characteristics: Single stone with desert weathered exterior. Saw cut and broken surfaces reveal relatively coarse grained texture of dark brown grains set in a yellow-brown groundmass. Petrography: (C. Agee, UNM) This meteorite is an equilibrated orthopyroxenite with ~95% pyroxene, and minor amounts of augite, chromite and iron-oxide. No olivine or plagioclase were detected. Geochemistry: (C. Agee, UNM) Low-Ca pyroxene Fs27.3±0.6Wo3.6±1.0, Fe/Mn=27±0, n=5. Classification: Diogenite Specimens: 22 g including a probe mount on deposit at UNM, Dustin Dickens holds the main mass. |
| Data from: MB108 Table 0 Line 0: |
Place of purchase: Mauritania Date: P 2016 Mass (g): 3800 Class: Diogenite Shock stage: moderate Weathering grade: moderate Ferrosilite (mol%): 27.3±0.6 Wollastonite (mol%): 3.6±1.0 Classifier: C. Agee, UNM Type spec mass (g): 22 Type spec location: UNM Main mass: Dustin Dickens Comments: Field name DD-52; submitted by C. Agee, UNM |
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