PALLASITES: A Rare View


The pallasites displayed on this page are seldom represented in private collections, and some not at all. All photos are courtesy of Dr. J. Piatek.

I'd like to express my appreciation to Dr. Piatek for sharing his rare pallasite collection on MeteoriteStudies.com.




Omolon—PMG

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A pallasite was seen to fall on May 16, 1981, and a single 253.5 kg mass was located a short time thereafter along the Omolon River in the Magadan region of the USSR. This mass was finally recovered a few years later. Omolon is one of only three verified pallasite falls, sharing this distinction with Marjalahti and Zaisho, and has a composition which places it in the main-group. The photo above shows a stunning 67.05 g slice of this rare fall, acquired from the Russian Academy of Sciences.



Giroux—PMG

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A single 4.275 kg pallasite was found by Francis Langill in Manitoba, Canada during the winter of 1954. Giroux has a composition which places it in the main-group. In the photo above is a 168 g partial slice, acquired in trade from the United States National Museum, Smithsonian Institution.



Phillips County—PMG-as

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A single 1.4 kg pallasite was found in Colorado, USA in 1935. Phillips County is unusually troilite-rich and has olivine with an anomalously high fayalite content, leading to its designation as an anomalous member of the main-group. Olivines occur as a mixture of rounded crystals and small, sharp fragments. The photo above shows a 94.4 g partial slice, acquired from the Jim Schwade Collection, previously obtained from David New following acquisition from Arizona State University, Center for Meteorite Studies.



Milton—ungrouped

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A single 2,038 g pallasite was found in Missouri, USA in October 2000. Olivine comprises ~73 vol% in Milton, which, along with the FeNi-metal, is chemically different from other pallasites. In addition, Milton also has unique O-isotope ratios, suggesting an origin from a previously unsampled asteroid. The photo above shows a 75 g slice from the 1,340 g main mass purchased from the finder.
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Eagle Station—PES

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A single 36.3 kg pallasite was found in Kentucky, USA in 1880. Eagle Station is the type specimen for a unique pallasite group consisting of Eagle Station, Cold Bay (see below), Itzawisis, Karavannoe, and Oued Bourdim. These pallasites have different metal and olivine compositions than those of the main-group clan. Shown in the photo above is a 185 g end section, acquired from the Jim Schwade Collection, previously part of the Vienna Museum Collection.
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Cold Bay—PES

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Many corroded fragments of this pallasite, having a combined weight of 320 g, were found in Alaska, USA in June 1921. This "silicated rust" has experienced selective corrosion of kamacite, i.e., the fine kamacite that was originally a constituent of plessite has been oxidized. Cold Bay is one of the five representatives of the Eagle Station group. Although they all share similar compositions, Cold Bay is derived from a more evolved magma than that which formed Eagle Station. The photo above shows a 20 g fragment, acquired in trade from the United States National Museum, Smithsonian Institution.



Itzawisis—PES

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A fresh meteorite weighing 350 g was found in Namibia in 1946, but the main mass was discovered to be missing some years ago. Itzawisis is one of five members composing the anomalous Eagle Station group. Angular silicates constitute ~75 vol%, while the remainder consists of FeNi-metal with accessory troilite, chromite, and whitlockite. These pallasites have the highest Fa value and the highest Ni content of all other pallasites, and their chromium and oxygen isotope systematics suggest that a genetic relationship (i.e., same parent body) exists between the Eagle Station group and the CV carbonaceous chondrites. The photo above shows both sides of a 37 g partial slice of Itzawisis, acquired from a major institution.



Newport—PMG

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A single 5,600 g pallasite was found in Arkansas, USA in 1923, and described by Harvey Nininger. Newport contains an unusually low olivine proportion of 37 vol%. It contains minor daubreelite and pentlandite associated with troilite, mackinawite, and native copper, reflecting low temperature reactions. In the photo above is a 122 g partial slice, acquired from the Jim Schwade Collection, previously obtained from David New following acquisition from Arizona State University, Center for Meteorite Studies.



Dora—PMG

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A single, 7.6 kg, fusion crusted pallasite was unearthed by a farmer plowing in New Mexico, USA around 1955. It was left beside a fence row for about 10 years until it was recognized as a meteorite in 1967. The angular olivines in Dora are indicative of early shock fracturing followed by a period of annealing. The photo shown above is a 157 g partial slice, acquired from the Robert Haag Collection, previously obtained from the Institute of Meteoritics, University of New Mexico.



Finmarken—PMG

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A single 77.5 kg pallasite was found in Finmark, Norway in 1902. This pallasite is unusual for its Ir enrichment and moderate As and Au enrichment in metal. It also has the highest measured olivine content in a pallasite, with at least 78 vol%. The photo of Finmarken shown above is a 77 g partial slice, acquired from the Robert Haag Collection.



Krasnojarsk—PMG-am

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A pallasite weighing 700 kg was found by Johan Mettich on Mount Emir in Siberia, near Krasnoyarsk, in 1749. The mass was later described by the German naturalist Peter Simon Pallas, for whom the meteorite group would later be named. In 1804, in an effort to prevent rust, William Thomson applied nitric acid to this meteorite and discovered the "Widmanstätten structure". Krasnojarsk has the highest content of Co, As, and Sb, and the lowest Ni and Cu, leading to its designation as an anomalous member of the main-group. The photo above shows an 86 g individual, within which are numerous voids that attest to extensive terrestrial weathering. It was acquired from the Jim Schwade Collection, previously obtained from the Bartoschewitz Meteorite Laboratory. Click here to see a 23 g historical Krasnojarsk specimen, acquired in trade from the United States National Museum, Smithsonian Institution, previously obtained from the Bosch Collection.



Acomita—PMG

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A single 3,956 g pallasite was found beside the road in New Mexico, USA in June 1962, by a man changing a tire. After utilizing the stony-iron to prop up the axle, he tossed it in the back of the truck. Acomita is a typical member of the main-group pallasites, which experienced efficient fractional crystallization, followed by impact mixing of fractured mantle olivine with molten core iron very early in Solar System history. The photo of Acomita shown above is a 160 g partial slice, acquired from the Robert Haag Collection, previously obtained from Arizona State University, Center for Meteorite Studies.



Mount Dyrring—PMG

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Pallasite fragments having a combined weight of 11.3 kg were found in New South Wales, Australia in 1903. The main mass remains in the Australian Museum in Sydney. The metal in Mount Dyrring has been oxidized during its long terrestrial residence. The photo above shows a 67 g end section, acquired from the Robert Haag Collection. Click here to see the natural surface on the reverse side of this end section.


CONTINUE TO PALLASITES: A Rare View [ PART II ]



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