Meteorite, Sericho, Stony Iron Pallasite
Sericho meteorites are a captivating subset of space rocks that have gained significant attention in the scientific community and among collectors worldwide. These meteorites were discovered in Kenya’s Sericho area, located near the border with Somalia, hence the name. What distinguishes Sericho meteorites from others is their unique shape and structure.
Unlike typical meteorites, which often come in recognizable shapes like spheres or fragments, Sericho meteorites are known for their intriguing twisted and sculptural forms. They resemble long, sinuous shapes with intricate patterns and surface textures, resembling abstract sculptures rather than conventional meteorite specimens. This distinctive appearance is believed to be the result of their journey through Earth’s atmosphere, where they experienced intense heat and pressure, causing them to deform and shape in unusual ways.
Scientists classify Sericho meteorites as a type of pallasite, a rare class of stony-iron meteorites that contain olivine crystals embedded in an iron-nickel matrix. Pallasites are prized for their beauty and scientific value, providing insights into the formation and evolution of asteroids. However, Sericho meteorites exhibit a unique variation of pallasite known as a siderolite, which contains both metallic and stony components. This composition adds to their allure and scientific interest.
The discovery of Sericho meteorites has sparked considerable excitement among meteorite enthusiasts and collectors. Their aesthetic appeal, combined with their rarity and unusual origin, makes them highly sought after in the meteorite market. Additionally, their relatively recent discovery means that specimens are still being recovered, adding to their allure for collectors and researchers alike.
Stony Meteorites: Witness to Stellar Birth
Comprising approximately 95% of all meteorite falls, stony meteorites, as the name suggests, are primarily composed of silicate minerals. Within this group, there are further subdivisions based on mineral composition and texture, such as chondrites, achondrites, and carbonaceous chondrites.
Chondrites: Among the most common type of meteorites, chondrites are primitive remnants of the early solar system, dating back over 4.5 billion years. They contain small spherical structures called chondrules, which are believed to have formed in the protoplanetary disk around the young Sun. These chondrules are composed of minerals like olivine and pyroxene, encapsulating the conditions of the nascent solar system. The study of chondrites provides valuable information about the processes of planetary accretion and differentiation.
Achondrites: Unlike chondrites, achondrites lack chondrules and exhibit evidence of igneous processing, indicating that they originated from larger planetary bodies with internal differentiation. These meteorites often resemble terrestrial rocks, with mineral compositions similar to basalts and gabbros found on Earth. Achondrites are thought to originate from the crust or mantle of differentiated bodies such as asteroids or even Mars. By analyzing the mineralogy and isotopic signatures of achondrites, scientists gain insights into the geological history and differentiation processes of planetary bodies beyond Earth.
Carbonaceous Chondrites: Renowned for their high carbon content and volatile-rich composition, carbonaceous chondrites are among the most primitive meteorites, containing complex organic molecules and water-bearing minerals. These meteorites offer tantalizing clues about the conditions that prevailed in the early solar system, including the delivery of water and prebiotic molecules to Earth. Scientists believe that carbonaceous chondrites may have played a crucial role in seeding the primordial Earth with the necessary ingredients for life.
Iron Meteorites: Relics of Cosmic Cores
Comprising about 5% of meteorite falls, iron meteorites stand out for their high iron and nickel content, often accompanied by traces of other elements like cobalt and phosphorus. These meteorites are remnants of the cores of differentiated bodies such as asteroids or protoplanets, where intense heat and pressure led to the segregation of metallic alloys.
Octahedrites: Characterized by a distinctive crystalline structure known as a Widmanstätten pattern, octahedrites are the most common type of iron meteorites. This pattern forms as a result of slow cooling over millions of years within the core of a planetary body, allowing nickel-iron crystals to grow into elongated shapes. The presence of the Widmanstätten pattern serves as a signature of extraterrestrial origin and provides insights into the cooling rates and thermal histories of parent bodies.
Hexahedrites: Unlike octahedrites, hexahedrites exhibit a cubic crystal structure and are relatively rare compared to their octahedral counterparts. These meteorites likely formed under different cooling conditions within the cores of larger asteroids or protoplanets. The study of hexahedrites helps scientists understand the diversity of parent bodies in the early solar system and the processes that governed their differentiation.
Ataxites: Ataxites represent a minor subclass of iron meteorites characterized by their high nickel content and lack of a distinct crystalline structure. These meteorites likely originated from the outer regions of planetary cores, where nickel concentrations were higher. The study of ataxites provides valuable information about the chemical composition and thermal evolution of parent bodies, offering clues about the conditions prevailing in the early solar system.
Stony-Iron Meteorites: Bridging the Divide
Stony-iron meteorites, as the name implies, represent a hybrid of stony and iron compositions, with roughly equal proportions of silicate minerals and metallic alloys. These meteorites are thought to originate from the boundary regions between a differentiated body’s mantle and core, where material mixing occurred due to impacts or geological processes.
Pallasites: Gem embedded Nickel Iron:
Pallasites: Pallasites are one of the most visually striking meteorite types, characterized by their beautiful olivine crystals embedded in a metallic matrix. These meteorites likely formed at the interface between the core and mantle of differentiated bodies, where molten metal percolated through fractures and filled cavities within the silicate matrix. The study of pallasites provides insights into the dynamics of core-mantle interactions and the mixing of materials in the early solar system.
Mesosiderites: Mesosiderites are stony-iron meteorites composed of roughly equal parts of silicate minerals and metallic alloys. Unlike pallasites, which exhibit a distinct separation of metal and silicate phases, mesosiderites show evidence of intense brecciation and mixing, indicating violent processes within the parent body. These meteorites likely originated from the crust or mantle of large differentiated bodies, where impacts or tectonic activity led to the commingling of materials.
IAB Irons: IAB iron meteorites represent a transitional group between iron and stony-iron meteorites, exhibiting a mixture of metallic alloys and silicate inclusions. These meteorites often contain complex textures and mineral compositions, suggesting a heterogeneous parent body with a history of geological activity and differentiation. The study of IAB irons provides valuable insights into the processes of planetary formation and differentiation in the early solar system.
Prehistoric 101 (Learn about fossils, minerals, and meteorites)
What is a Meteorite? Nickel Iron
What is a Meteorite?
The Meteoritical Society Database
