Telluric iron

Most iron on Earth is mixed with rocks.

But some iron is pure metal. This is called telluric iron. It is very hard to find. Most of it is in Greenland.

It can be found in cracks in the ground. Long ago, people used this metal for tools. They made small knives from it. They even made thin metal discs. This iron is a very rare treasure.

Most iron on Earth is mixed with other rocks. But telluric iron is different. It is pure metal found right here on our planet. The name comes from the Latin word Tellus, which means Earth.

This metal is very rare. Most of it is in Greenland. It often forms in dikes. These are cracks in rocks filled with lava.

There are two main types of telluric iron. Type 1 has a lot of carbon. It is very hard and brittle. This means it can snap easily. It is often found in huge boulders.

Type 2 has much less carbon. This metal is soft and easy to shape. This is called malleable. The Inuit people used Type 2 iron for tools. They made knives and small discs. They would crush the rock to find tiny iron grains. Then, they hammered the grains into thin plates. These plates were set into bone handles.

This made tools that worked like a saw.

Telluric iron is a very special kind of metal. Most iron on Earth is found as ore, which is a rock that contains iron. Almost all the metal iron on our planet turned into iron oxides long ago. This happened during a time called the Great Oxidation Event about 2 billion years ago. Telluric iron is different because it is found as a pure metal. The name comes from the Latin word Tellus, which means Earth. This name helps people know it came from our planet and not from outer space.

This metal forms deep inside the Earth's mantle and crust. It is often found in dikes, which are cracks in bedrock filled with lava. It can also be found in extrusions where molten rock flowed onto the surface. In Greenland, the iron is often found near graphite-rich feldspar. This special rock might help the iron stay as a pure metal. The iron can appear in many different shapes. It might look like tiny grains inside basalt rock. It can also form large, pea-sized droplets or even huge, heavy boulders.

Scientists have studied this metal for a long time. In 1870, Adolf Erik Nordenskiöld found large iron boulders near Disko Bay. At first, he thought the metal came from meteorites from space. Later, Gustav Nauckhoff traveled to Greenland in 1871 to collect large samples. He brought three big pieces back to Europe for study. These heavy blocks are still kept in museums today. One 25-ton block is in Stockholm, Sweden. Another 6.6-ton block is in Copenhagen, Denmark. A 3-ton block is kept in Helsinki, Finland.

There are two main groups of telluric iron. Type 1 iron has a lot of carbon, usually over 2.0%. It is very hard and brittle, which means it can snap easily. It often looks like massive boulders that weigh many tons. Type 2 iron has much less carbon, usually less than 0.7%. This type is malleable, which means it is soft enough to shape. It is usually found as small grains inside basalt rock. These grains are often only 1 to 5 millimeters wide.

The Inuit people were the only ones to use this metal for tools. They used Type 2 iron to make very useful items. They would crush basalt rock to find the small iron grains. Then, they hammered these grains into thin, flat discs. They put these discs into bone handles to make knives or ulus. These tools had edges that worked like a saw. This shows how people can use the rare gifts of the Earth.

Telluric iron is a rare form of elemental iron that originated on Earth. Most iron on our planet is found as iron ore, which is a mineral containing iron mixed with other elements. This is because nearly all metallic iron was transformed into iron oxides during the Great Oxidation Event about 2 billion years ago. Telluric iron is unique because it exists in a metallic form rather than as an oxide. Its name comes from the Latin word "Tellus," meaning Earth. This distinguishes it from meteoric iron, which comes from outer space.

This metal forms deep within the Earth's mantle and crust. In Greenland, the primary deposits are found in dikes or extrusions. A dike is a fracture in bedrock that has been filled with lava. These deposits often appear alongside graphite-rich feldspar. Scientists believe this carbon-rich environment might prevent the iron from oxidizing. There are several theories about how this happens. It is possible the metal escaped oxidation during geological shifts. Alternatively, iron ores and coal may have subducted and been naturally smelted by the heat of the lava.

Telluric iron is categorized into two distinct types based on carbon content. Type 1 is a white nickel cast-iron containing between 1.7% and 4% carbon. It also contains between 0.05% and 4% nickel. This type is very hard and brittle, making it difficult to shape. It often appears as massive extrusions or boulders weighing tens of tons. Type 2 iron is different because it contains much less carbon, typically under 0.7%. It is a malleable nickel-iron, meaning it is soft enough to be shaped by hammering. Type 2 is usually found as small grains, measuring 1 to 5 millimeters, embedded in basalt rock.

These two types show very different physical properties. Type 1 iron has a structure made of pearlite and cementite, also called cohenite. Its ferrite grains are usually about one millimeter in size. If you were to saw a Type 1 boulder in half, you would find a thick outer shell. The inside is often a porous, sponge-like material that can pulverize when struck. Type 2 iron is much easier to work with. The local Inuit people used Type 2 iron to create practical tools. They would crush basalt to release the small iron grains and hammer them into thin, coin-sized discs.

The history of discovering telluric iron is a story of scientific correction. In 1870, Adolf Erik Nordenskiöld found large iron boulders near Disko Bay, Greenland. He initially believed the metal was meteoric because it contained nickel and Widmanstätten structures. These structures are specific crystalline patterns found in certain metals. In 1871, Gustav Nauckhoff collected large samples and brought them to Europe. These massive pieces are still on display in museums today. A 25-ton block is in Stockholm, a 6.6-ton block is in Copenhagen, and a 3-ton block is in Helsinki.

It was K. J. V. Steenstrup who eventually proved the iron was terrestrial. In 1879, he discovered Type 2 iron grains inside basalt in an old grave at Ekaluit. He noticed the iron was embedded in volcanic basalt that matched the local bedrock. This proved the metal was born from the Earth, not from space. He also observed that the iron was soft enough for the Inuit to use for knives. His findings were confirmed by experts like J. Lawrence Smith and Joh Lorenzen. This discovery changed how scientists understood the presence of elemental iron on our planet.

Today, we know that telluric iron is extremely rare. While minor deposits have been reported in places like Scotland, Ireland, and Russia, the Greenland deposits are the only major ones. The Inuit were the only people to make practical use of this rare material. They created unique tools by inserting overlapping iron discs into bone handles. This created an edge that functioned like a combination of a knife and a saw. Understanding telluric iron helps scientists learn about the chemical processes happening deep inside the Earth's crust.