regmaglypts

50 Shades…. Of Science


Sometimes I sit in the dark and touch my meteorite.
A firm and heavy iron meteorite belonging to the chemical group IIAB, its coarse octahedrite structure feels rough beneath my eager fingers, its strange regmaglypted surface the result of hot and heavy atmospheric ablation at 5.6km above the Earth’s surface.

I think about the 93% iron, 5.9% nickel, 0.42% cobalt, 0.46% phosphorus, and 0.28% sulfur that lends it most of its mass. How deeply that mass must have plunged into the fertile Earth waiting below, the impact crater filling with hot and gooey tektites and the Earth releasing her dirty, dirty meteoric dust with a shudder and groan.

I can almost taste the trace amounts of germanium and iridium on my wanting tongue, my bottom lip quivering as I think about other minerals present: taenite, plessite, troilite, chromite, kamacite, and schreibersite. Mmmmm.
Sometimes I sit in the dark and touch my meteorite.

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Sikhote-Alin individual iron meteorite. Structural classification is coarsest octahedrite type IIB. Weight is 85 grams. Well developed regmaglypts (thumb prints) resulted from ablation of the meteoroid as it melted during flight. Stippled areas, on an otherwise smooth surface, are splash fields where molten iron-nickel splashed across the surface during flight through the atmosphere, marring what would have become a  pristine fusion crust. The Sikhote-Alin Meteorite was an observed fall on the Sikhote-Alin mountains in Siberia in 1947. An estimated 70 Tonnes of this iron-nickel meteorite made it to the ground.

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Campo del Cielo iron meteorite. Structural classification is coarse octahedrite. Upper photo shows wonderfully developed regmaglypts, also referred to as “thumbprints”. The regmaglypts formed while the meteoroid ablated during passage through the atmosphere. The Campo del Cielo meteorites come from Argentina, where they are believed to have fallen between 4,000 and 5,000 years ago. Nickel-iron meteorites, such as this one, are fragments of the cores of larger ancient asteroids (similar to Earths iron core), that have been shattered by impacts with other asteroids. After spending 4,500 million years in space this piece of ancient iron core found its way to Earth from the asteroid belt between Mars and Jupiter. The lower photo shows the cut, polished and acid etched sliced side of the upper photo. The slice displays the classic Widmanstatten pattern (a.k.a. Thomson structure) found in some iron-nickel meteorites. This pattern results from the interweaving of crystals from two iron alloys, kamacite (low nickel) and taenite (high nickel). The Widmanstatten pattern is diagnostic of meteorites as this pattern cannot be duplicated in laboratories on Earth. To form this pattern the iron core of the asteroid must cool no faster than a couple of degrees every million years

Campo del Cielo iron meteorite. Structural classification is coarse octahedrite. Weight is 3 kilograms. This photo shows wonderfully developed regmaglypts, also referred to as “thumbprints”. The regmaglypts formed while the meteoroid ablated during passage through the atmosphere. The Campo del Cielo meteorites come from Argentina, where they are believed to have fallen between 4,000 and 5,000 years ago. Nickel-iron meteorites, such as this one, are fragments of the cores of larger ancient asteroids (similar to Earths iron core), that have been shattered by impacts with other asteroids. After spending 4,500 million years in space this piece of ancient iron core found its way to Earth from the asteroid belt between Mars and Jupiter.

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Sikhote-Alin individual iron meteorite. Structural classification is coarsest octahedrite type IIB. Weight is 100 grams. Well developed regmaglypts (thumb prints) resulted from ablation of the meteoroid as it melted during flight.  The Sikhote-Alin Meteorite was an observed fall on the Sikhote-Alin mountains in Siberia in 1947. An estimated 70 Tonnes of this iron-nickel meteorite made it to the ground. Two forms of this meteorite exist. The “Individual” that is shown in this picture is a broken piece of the main mass that continued to “burn up” in the atmosphere before hitting the ground. The “Shrapnel” form consists of torn and twisted fragments that formed when the meteoroid exploded near the ground or upon impaction. The individuals of the Sikhote-Alin fall are one of the most sought after meteorites by collectors because of their exquisite shapes and character. 

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Canyon Diablo iron meteorite. Structural classification is coarse octahedrite. Weight is 133 grams. This photo shows  developed regmaglypts, also referred to as “thumbprints”. The regmaglypts formed while the meteoroid ablated during passage through the atmosphere. The Canyon Diablo meteorites come from the famous Barringer Crater (aka Meteor Crater) near Flagstaff, Arizona, USA,  where they are believed to have fallen about 50,000 years ago. Iron-nickel meteorites, such as this one, are fragments of the cores of larger ancient asteroids (similar to Earths iron core), that have been shattered by impacts with other asteroids. After spending 4,500 million years in space this piece of ancient iron core found its way to Earth from the asteroid belt between Mars and Jupiter. The photo of Meteor Crater shown above is about 1 mile wide and 600 feet deep and is one of the best preserved meteorite craters in the world.