--- title: "Stony-Iron Meteorite | Intro to Astronomy" description: "Stony-iron meteorites mix silicate rock and iron-nickel metal, revealing how asteroid interiors differentiated in Intro to Astronomy." canonical: "https://fiveable.me/intro-astronomy/key-terms/stony-iron-meteorite" type: "key-term" subject: "Intro to Astronomy" unit: "Unit 14" --- # Stony-Iron Meteorite | Intro to Astronomy ## Definition A stony-iron meteorite is a space rock with both silicate minerals and iron-nickel metal. In Intro to Astronomy, it is a rare clue to how asteroid interiors formed and mixed. ## What It Is A stony-iron meteorite is a meteorite made of a near-even mix of rocky silicate minerals and metallic iron-nickel. In Intro to Astronomy, you usually meet it as one of the rarest meteorite classes and as evidence that some early solar system bodies developed layered interiors, not just uniform rock. The mix matters. If a body starts hot enough, heavy metal tends to sink inward and lighter silicate rock stays farther out, a process called differentiation. A stony-iron meteorite seems to sample a transition zone between those layers, so it preserves material from the boundary where core metal and mantle rock interacted. That makes it different from a plain stony meteorite, which is mostly silicate, or an iron meteorite, which is mostly metal. One famous subtype is the pallasite. Pallasites often show olivine crystals, which can look like greenish gems, suspended in metal. That texture is not just pretty, it tells you the rock cooled and solidified in a very specific environment inside a parent body. When you see a polished slice of a pallasite, you are looking at a snapshot of internal structure, not just a random chunk of asteroid debris. Astronomy classes use stony-iron meteorites to talk about parent bodies, especially large asteroids or planetesimals that were heated early in solar system history. Heating could come from short-lived radioactive isotopes, impacts, or both. Once melting begins, dense metal can collect toward the center and silicates separate outward. A stony-iron sample suggests that some material escaped from the border zone before that separation was perfectly complete. Because they are so rare, stony-iron meteorites do not show up as often as chondrites or ordinary stony meteorites in collections or lab sets. When they do appear, they are useful for comparing texture, density, and composition. In an astronomy lab, you might identify them by their metallic shine, embedded crystals, and mixed mineral-metal structure rather than by any one single color or shape. ## Why It Matters Stony-iron meteorites matter in Intro to Astronomy because they give you a direct clue about how small rocky bodies evolved from simple rubble into layered objects with cores and mantles. That is the same basic idea behind the internal structure of planets, just on a smaller scale. They also connect meteorites to planetary differentiation. If you know that heavy iron sank inward and silicates moved outward, a stony-iron sample makes that process easier to picture. It is evidence that the separation was happening, but not fully finished, which is why these meteorites are so informative. This term also shows up when you compare meteorite classes. A lab question might ask you to separate stony-iron from iron meteorites or stony meteorites by texture and composition. If you can identify the mixed metal and silicate makeup, you can reason through where the specimen came from and what it reveals about the parent body. For astronomy, that is the big payoff: meteorites are not just space rocks. They are physical records of early solar system processes, and stony-irons preserve one of the clearest records of interior mixing and layering. ## Connections ### Pallasite Pallasite is the best-known subtype of stony-iron meteorite. It is the one with olivine crystals set in metallic iron-nickel, which gives it the famous gem-like appearance in thin slabs. If you are identifying samples, pallasite is the visual example most likely to come up when someone says stony-iron. ### [Iron Meteorite](/intro-astronomy/key-terms/iron-meteorite) Iron meteorites are almost all metal, while stony-irons contain a major silicate component too. Comparing the two helps you think about differentiation, because both are tied to internal layering in early asteroids or planetesimals. The difference is where in the parent body the material came from. ### [Stony Meteorite](/intro-astronomy/key-terms/stony-meteorite) Stony meteorites are mostly silicate rock, so they represent the rocky side of meteorite classification. Stony-irons sit between stony and iron meteorites in composition, which makes them useful for seeing the boundary between mantle-like material and metal-rich interior material. ### [Widmanstätten Pattern](/intro-astronomy/key-terms/widmanstatten-pattern) Widmanstätten Pattern is a cooling texture you often associate with iron-rich meteorites. It is not the same thing as the crystal texture in a stony-iron meteorite, but both can point to slow cooling inside a parent body. That makes texture a big clue in meteorite identification. ## On the AP Exam A quiz or lab question may show you a meteorite photo or thin section and ask you to identify the specimen from its mixed metal-and-silicate texture. You might also need to explain what that mix says about the parent body, especially whether it underwent differentiation. If you are comparing meteorite types, use stony-iron as the in-between class, not fully rocky and not fully metallic. For short responses, a strong answer usually names the composition, then links it to core-mantle boundary material in an asteroid or planetesimal. If the question mentions pallasite, connect the olivine crystals to the metallic matrix and the idea of slow cooling in a layered interior. ## Stony-Iron Meteorite vs Iron Meteorite Iron meteorites are mostly iron-nickel metal, with little to no silicate rock. Stony-iron meteorites contain a substantial mix of both metal and silicate minerals, so they show a transition zone rather than a mostly metallic core sample. ## Key Takeaways - A stony-iron meteorite is a rare meteorite made of both silicate minerals and iron-nickel metal. - Its mixed composition points to a parent body that had started to differentiate into core and mantle material. - Pallasites are a famous type of stony-iron meteorite, known for olivine crystals in a metallic matrix. - In Intro to Astronomy, stony-iron meteorites are evidence for the internal structure of early asteroids and planetesimals. - You usually identify them by their unusual combination of rocky and metallic textures, not by a single color or surface feature. ## FAQs ### What is a stony-iron meteorite in Intro to Astronomy? It is a meteorite that contains both silicate rock and iron-nickel metal in roughly comparable amounts. In astronomy, that mix is a clue that the meteorite came from a layered parent body, likely near the boundary between core and mantle material. ### How is a stony-iron meteorite different from an iron meteorite? An iron meteorite is mostly metal, while a stony-iron meteorite has a major rocky silicate component too. That difference matters because stony-irons sample the transition between metallic interior and rocky exterior, not just the core. ### What is a pallasite? A pallasite is a type of stony-iron meteorite with olivine crystals embedded in metal. It is one of the most recognizable meteorite textures in astronomy labs because the crystal-metal mix can look gem-like when polished. ### Why are stony-iron meteorites so rare? They represent material from a very specific zone in a differentiated parent body, where metal and silicate were still mixed at the boundary between core and mantle. That combination is less common than pure metal or pure rock, so only a small fraction of meteorites are stony-irons. ## Related Study Guides - [14.2 Meteorites: Stones from Heaven](/intro-astronomy/unit-14/2-meteorites-stones-heaven/study-guide/2N2c4WGxrY4R77zE) ## About This Document Canonical Fiveable pages are available as Markdown at the same path plus `.md`. - [llms.txt](https://fiveable.me/llms.txt): index of Fiveable's sections and URL patterns - [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing - [MCP server](https://fiveable.me/mcp): call Fiveable as tools instead of fetching pages (`https://fiveable.me/api/mcp`) - [MCP server for AP teachers](https://fiveable.me/mcp/teachers): a teacher's classes, assignments and AP-rubric grading (`https://fiveable.me/api/mcp/teacher`) ## Structured Data ```json {"@context":"https://schema.org","@graph":[{"@type":"LearningResource","@id":"https://fiveable.me/intro-astronomy/key-terms/stony-iron-meteorite#resource","name":"Stony-Iron Meteorite | Intro to Astronomy","url":"https://fiveable.me/intro-astronomy/key-terms/stony-iron-meteorite","learningResourceType":"Concept explainer","educationalLevel":"AP® / High School","about":{"@id":"https://fiveable.me/intro-astronomy/key-terms/stony-iron-meteorite#term"},"audience":{"@type":"EducationalAudience","educationalRole":"student"},"dateModified":"2026-07-03T02:22:21.332Z","isPartOf":{"@type":"Collection","name":"Intro to Astronomy Key Terms","url":"https://fiveable.me/intro-astronomy/key-terms"},"author":{"@type":"Organization","@id":"https://fiveable.me/editorial#content-team","name":"Fiveable Content Team","url":"https://fiveable.me/editorial","parentOrganization":{"@id":"https://fiveable.me/#organization"},"member":[{"@type":"Person","name":"Amanda DoAmaral","sameAs":["https://www.linkedin.com/in/adoamaral"]},{"@type":"Person","name":"Becky Bahr","sameAs":["https://www.linkedin.com/in/becky-bahr-b52743132"]}]},"publisher":{"@type":"Organization","name":"Fiveable","url":"https://fiveable.me"}},{"@type":"DefinedTerm","@id":"https://fiveable.me/intro-astronomy/key-terms/stony-iron-meteorite#term","name":"Stony-Iron Meteorite","description":"A stony-iron meteorite is a space rock with both silicate minerals and iron-nickel metal. 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