The Earth has some pretty spectacular and rare minerals. We’re not talking about the likes of diamonds or rubies, we’re talking about the extremely rare minerals that are just out of this world — sometimes, quite literally. Krotite is one such mineral, a cosmic relic that formed billions of years ago, long before Earth existed.

It’s one of the oldest minerals in the Solar System

Krotite is no ordinary mineral. It formed at extremely high temperatures—conditions found in the violent infernos of dying stars or the swirling disk of material that birthed our Sun.

The mineral was discovered in 2011 in a fragment of a meteorite in Africa. The meteorite, called NWA 1934, fell to Earth after billions of years wandering the cosmos. It can’t be formed naturally on Earth now because it requires high temperatures and low pressures; on planets like Earth, temperatures increase the deeper you go into the subsurface, but so does pressure. You’d need a hot environment on the surface to generate krotite, which doesn’t naturally occur.

The conditions required to generate krotite are similar to those in the early days of the Solar System, some 4.6 billion years ago. This makes it likely one of the oldest minerals in our corner of the universe.

Meteorites act as time capsules, preserving minerals like krotite in their pristine state. Unlike Earth’s crust, which is constantly reshaped by volcanic activity, erosion, and tectonic forces, meteorites remain largely untouched. This allows scientists to study krotite as it was billions of years ago, offering insights into the early Solar System.

“Krotite is a low-pressure CaAl₂O₄ mineral, likely formed by condensation or crystallization from a melt in the solar nebula. This is the first reported occurrence of krotite in nature and it is one of the earliest minerals formed in the solar system,” researchers analyzing the mineral wrote in 2011.

Cosmic concrete

Its composition and structure reveal clues about the conditions that existed when the solar system was forming. Krotite is a mix of calcium, aluminum, and oxygen arranged in a unique crystalline pattern (with the molecular formula CaAl₂O₄). This formation could only happen at temperatures above 1,500 degrees Celsius, similar to those found in the earliest protoplanetary disk.

Inadvertently, however, we humans have generated something pretty close to krotite.

Some types of man-made concrete (specifically, calcium aluminate cement) are very similar. In fact, the most similar type of concrete (monocalcium aluminate) shares the same chemical formula but has a different atom arrangement (much like diamond and graphite have the same chemistry but different arrangement). Dmitryivanovite, another mineral found only in meteorites, also has a similar chemical formula but a different arrangement.

Both minerals were named after geologists. Krotite was named after Alexander N. Krot (b. 1959), a cosmochemist at the University of Hawaii who made important contributions to the understanding of early solar system processes. Meanwhile, Dmitryivanovite was named after geologist Dmitriy A. Ivanov.

Geology is everywhere

For scientists, analyzing krotite is like reading a cosmic history book. Each part of the mineral holds secrets about the solar system’s infancy, offering answers to questions about how planets like ours came to be.

For instance, findings support the theory that CAIs, and minerals like krotite, condensed from a hot, gaseous cloud of material that surrounded the newborn Sun. By studying such minerals, scientists gain insights into the processes that led to the creation of planets and other celestial bodies.

Researchers even have a theory on how this part of the mineral formed. Initially, either by condensation or crystallization, in the high-temperature solar nebula environment. Later, the inclusion interacted with a hot gas rich in aluminum but low in calcium, triggering chemical reactions that created layers of different minerals around it. Partial melting events followed, which caused some minerals to corrode and new ones (like melilite and perovskite) to crystallize in between. Cooler processes then introduced chlorine and iron and finally, Earth’s weathering processes filled cracks in the inclusion with hydroxides.

This small, unassuming mineral may be older than Earth itself. Krotite reminds us of the vast timescales and surprising forces at play in shaping the universe. It’s a reminder that geology is above our heads as much as it is beneath our feet — we just need to look for it.