Space top header

Stony-Iron Meteorites

Meteorites can be classified according to their composition (just like rocks here on Earth). And given our nature to turn virtually any rock into a gemstone, the same can also be done with meteorites. The classification of stony-iron meteorites is rather small and consist of really only two groups: pallasites and mesosiderites. It is within this group that the focus of this website will be on - pallasites.

Olivine crystals exposed
This is an image showing what exposed olivine crystals look like in this uncut and unpolished pallasite.
Photograph by Qynne Arnold © Steve Arnold Meteorites

Stony-iron meteorites refers to the small group of meteorites that are composed of some metallic alloy, usually in the form of iron and/or nickel. The majority of meteorites - about 86% - are known as stony meteorites because they do not contain any metallic element in their material composition. So it comes to as no surprise that the rarity of pallasites results in their finds to be celebrated and much attention drawn to the total weight recovered.

Origins

Pallasites obtain their name from the German doctor, Peter Pallas, who was the first to describe this iron meteorite in 1772. Pallasites are a rare group of meteorites and are consequently hard to come by. It is estimated that only about 10 tons of this meteorite type have been recovered, which amounts to only 3.5% of the total weight recovered when totaled with all the known meteorites that have been discovered and retrieved.

The actual origins of pallasites is still currently under investigation. One hypothesis suggests that they may have originated from the core-mantle boundary of an asteroid which was shattered and torn apart as a result of impeding impact/collision from another or several asteroids. This hypothesis has led some to believe that pallasites may be leftovers from what may have been another planet that somehow was torn apart by a catastrophic event. Another theory suggests that impacts and impoundments have led to the mixing of core and mantle materials into a crystalline structure. 

Even though pallasites are rare, enough material has been recovered to allow scientists to continue their studies on this rock as well as material preservation within museums around the world.

Composition & Appearance

Pallasites are composed of olivine crystals within a matrix of nickel and iron. Differences in appearances exist between those that have been subjected to long periods of weathering and those that have not. Old pallasites will appear more sponge-like and “ugly” due to the discoloration of the olivine crystals (which will have turned a blackish color) and the fact that the olive crystals will have been weathered out of the matrix.

pallasite polished
An image detailing the interior of a cut and polished pallasite meteorite.
Photograph by Geoffrey Notkin © Oscar E. Monnig Meteorite Collection

On the other hand,  in “newer” pallasites, the olivine crystals will have retained an olive-green, almost crystal-clear composition and remained intact within the matrix. When sliced and polished, the olivine crystals are extremely evident, illuminating a greenish to amber hue depending upon the age of the pallasite. It is these types of un-weathered pallasites that are sought after by both gem collectors and sellers!

Properties

Specifications
Mineral Classification: Metals and intermetallic alloys
Chemistry: (Fe,Ni) + (Mg,Fe2+)2[SiO4]
   
Physical Properties
Crystallography: Isometric - Hexoctahedral
Cleavage: Indistinct
Tenacity:
Brittle
Hardness (Mohs): 4.0
Density:
7.90 (g/cm3)
Luminescence: None
Other: Magnetic
   
Optical Properties
Color:
Steel Gray to Iron Black
Transparency: Opaque
Luster: Metallic
   
Occurrences
Year Discovered: 1772
Common Associations: Cohenite, Daubréelite, Graphite, Moissanite, Oldhamite, Schreibersite, Taenite, Troilite, other meteorite minerals.
Common Impurities: Co, C, P, S
Type Locality: Near Krasnojarsk in the mountains of Siberia


Meteorite Jewelry

Most meteorites that fall to the Earth are not suitable for use in jewelry pieces or jewelry making. Of the known meteorites, only two types – pallasites and octahedrites – are currently used in jewelry. Material composition plays a key role; about 86% of the meteorites that are recovered fall into the “stony” category of meteorites. These types of meteorites are so named because they are either silicate-based or a type of basaltic/plutonic rock. In order to gain the most in terms of beauty and durability, only iron meteorites - which contain a mixture of both nickel and iron (nickel-iron alloys) – are used. Iron meteorites make up only 8% of the meteorites that fall on earth, with a smaller percentage being pallasites. This small category of meteorites are known as the iron meteorites – pallasites specifically are known as stony-iron meteorites – and are sought after by jewelers particularly for their look after they have been cut and polished. However, due to the rarity of pallasites in general, pallasite jewelry can be a one-of-a-kind of jewelry piece to own. When cut and polished, pallasites reveal the beautiful “free-floating” olivine crystals within the nickel-iron matrix.

pallasite pendant
A sample of the type of jewelry pieces made using pallasites.
This image features a beautiful pallasite pendant, which can be purchased
from Sciencemall-usa.com.
Photograph ©
Sciencemall-usa.com.

Pallasite pendant 14 kt gold
Another great example of a beautiful pallasite jewelry piece set in a 14 kt gold pendant.
This pendant is for sale and can be purchased at Ferbers.com.
Photograph © Ferbers.com.

Record Discoveries

Brenham-Strewn field, Kansas (2005): Recovered pallasite known as the Brenham pallasite. The world’s largest pallasite to-date was discovered by “professional meteorite hunter” Steve Arnold in late 2005. The total weight of the meteorite recovered was calculated to be 650 kg (1,400 lbs). According to the website dedicated to this find – World Record Meteorite – the author intends to keep the meteorite intact, in hopes that it will find a home in a museum or major institution.

Brenham-Strewn pallasite
This photo shows the world's largest pallasite ever recovered in its entirety.
Photograph by Geoffrey Notkin © Aerolite Meteorites

Fukang, China (2000): Recovered pallasite known as the Fukang pallasite. This amazing meteorite was discovered in the Xinjiang Province, near Fukang, China. Its initial weight was calculated at 1003 kg, but later it was cut with the main mass now weighing 420 kg. The main mass was first revealed in the States the the Tuscan Gem and Mineral show in 2005 and was later studied by several scientists from various universities. It is currently on display and part of the Southwest Meteorite Laboratory based in Arizona.

Chubut, Argentina (1951): Recovered pallasite known as the Esquel pallasite. This meteorite was discovered by a farmer in 1952 and bought over to the States in 1992. The mass recovered was estimated to weigh 1500 kg. The mass was eventually cut in numerous pieces and distributed among scientists, universities, museums and sellers/collectors. Scientific study of the Esquel pallasite estimates its age to be over 4.0 billion years old.

esquel
The above image shows a slice of the Esquel pallasite.
Photograph by Geoffrey Notkin © Aerolite Meteorites
Atacama Desert, Chile (1882): Recovered pallasite known as the Imilac pallasite. The discovery of this site was first documented in 1882 and pieces of the meteorite were taken from this region at the time of its discovery because it was thought that it was silver. It was later noted that it was in fact a stony-iron meteorite. Since then, people from around the world have visited the region in search for their own piece of a pallasite. Numerous masses have been found, with a total weight calculated at 920 kg. Specimens are in distribution among the mass market and websites selling pieces of the Imilac are not hard to come by.

imilac
The above image shows a slice of the Imilac pallasite.
Photograph by Geoffrey Notkin © Aerolite Meteorites

Gomel Region, Belarus (1810): Recovered pallasite known as the Brahin pallasite. This pallasite was discovered in 1810 and it is the second meteorite to have been found in Russia. Two masses were initially recovered but since then, several other masses have been retrieved, giving scientists an opportunity to study it as well as allowing gem sellers/collectors to distribute small slices within the mass market. Since its initial discovery, the total weight of all recovered pieces is estimated to be over 2000 kg. In 2002, another mass was found, weighing roughly 227 kg. The Brahin-strewnfield occurs along the area that as subject to radiation contamination from the 1982 Chernobyl disaster. This poses a risk for meteorite hunting in the area as well as the depth of which the masses are found in (as they can be contaminated with radiation).

References & Links of Interest

Aerolite Meteorites. <http://www.aerolite.org>. [retrieved 20 April 2010].

Brahin Pallasit Meteorite. <http://www.melvinsmeteorites.com/new12433.html>. [retrieve 22 April 2010].

Classic Gems Network. <http://www.gemstonediscovery.com/gem_pallasite.htm>. [retrieved 10 April].

Esquel. <http://www.k4zrd.com/Esquel.html>. [retrieved 22 April 2010].

Geology. <http://geology.com/meteorites/stony-iron-meteorites.shtml>. [retrieved 18 April 2010].

Meteorite, Pallasite from Chile! Imilac. <http://www.worthpoint.com/worthopedia/meteorite-pallasite-from-chile-imilac>. [retrieved 22 April 2010].

Meteorites and Their Properties. <http://meteorites.lpl.arizona.edu/composition.html>. [retrieved 26 April 2010].

Meteoroids and Meteorites. <http://www.solarviews.com/eng/meteor.htm>. [retrieved 26 April 2010].

Pallasites. <http://www.meteorlab.com/METEORLAB2001dev/pallas.htm>. [retrieved 8 April 2010].

Pallasite and Meteorite Jewelry. <http://www.allaboutgemstones.com/semi-precious_gems_meteorite.html> [retrieved 26 April 2010].

Pallasite Meteorites Pendant Jewelry. <http://www.sciencemall-usa.com/pamepeje.html>. [retrieved 20 April 2010]. 

Southwest Meteorite Laboratory. <http://www.meteoritelab.com/collection/fukang.php>. [retrieved 26 April 2010].

Stony iron meteorites. <http://www.haberer-meteorite.de/english/Stone%20iron%20meteorites.htm>. [retrieved 8 April 2010].

World Record Meteorite - largest oriented pallasite. <http://www.worldrecordmeteorite.com/>. [retrieved 14 April 2010].