7 Oldest Rocks Ever Discovered

The Earth is about 4.54 billion years old, plus or minus 50 million years, based on evidence from radiometric age-dating. Since the Earth’s crust is always changing, evidence of the earliest parts of the Earth’s formation are hard to come by. However, there have been several discoveries of terrestrial rock formations that are nearly as old as the Earth itself.

In addition to these ancient rock formations, some of the oldest rocks in the world came from outer space as either rock samples from the Moon or meteorites. All of these rocks, which are at least 3.5 billion years old, provide important information about the formation of the Earth.

7. Isua Greenstone Belt

Age: 3.7 – 3.8 billion years
Location: Greenland
Rock Type(s): tonalite, mafic rocks, metasedimentary rocks, banded iron formations, granite, and granodiorite

Isua Greenstone Beltphoto source: Alchetron

The Isua Greenstone Belt is one of the oldest rock formations on Earth, aged between 3.7 – 3.8 billion years. Since its discovery, the Greenstone Belt has been thoroughly studied since it houses one of the oldest and best preserved ancient plate tectonic sequences. Recent research uncovered the fossilized remains of cone-shape stromalites, which are layered mounds of sediment and carbonates that build up around colonies of microbes that grow on the floor of shallow seas or lakes.

At the time (2016), this discovery was believed to be the oldest fossils of living organisms ever found on Earth. However, a more recent study published in 2017 announced the discovery of microorganisms fossils at the Nuvvuagittuq greenstone belt, which is nearly a half-billion years older than the Isua Greenstone Belt.


6. Acasta Gneiss

Age: 3.58 – 4.031 billion years
Location: Northwest Territories, Canada
Rock Type(s): tonalite gneiss, mostly composed of quartz and feldspar

Acasta Gneissphoto source: Wikipedia

Prior to the discovery of the Nuvvuagittuq greenstone belt, the Acasta Gneiss was the oldest rock formation found on Earth, the oldest parts of which date back to about 4.031 billion years. However, due to the contention surrounding the methods used to determine the age of the Nuvvuagittuq rocks, many people still consider the Acasta Gneiss the oldest known intact crustal rock ever found.
The rock specimens were first discovered by Dr. Janet King in 1989. Due to its age, the Acasta Gneiss was formed during the Hadean, the earliest eon in Earth’s history and it is only about a half-billion years younger than the Earth itself.


5. Alan Hills 84001

Age: 4.091 billion years
Location: from Mars found in Alan Hills, Antarctica
Rock Type(s): composed of orthopyroxene, chromite, maskelynite, and iron-rich carbonate

Alan Hills 84001photo source: Wikipedia

Alan Hills 84001 (commonly abbreviated as ALH84001) is a meteorite that was found in Antarctica in 1984 – it is believed to be from Mars. The meteorite is famous for drawing international attention in 1996 when a group of researches from NASA’s Johnson Space Center in Houston announced they had spotted possible signs of Martian life in the meteorite.

The strongest evidence that the researchers presented for their claim was the existence of microscopic magnetite crystals that they said resembled ones created by microbes on Earth. However, most of the scientific community rejected their hypothesis. Despite the controversy, the researchers’ paper did influence the development of the new interdisciplinary field of astrobiology.


4. Genesis Rock

Age: 4.1 ± 0.1 billion years
Location: from the Moon
Rock Type(s): Anorthosite

Genesis Rock photo source: Wikipedia

The Genesis Rock is Moon rock sample collected during the Apollo 15 mission by astronauts James Irwin and David Scott from the Spur crater. The rock received its name because it was initially believed to have been a part of the Moon’s primordial crust, however more recent analysis places its age around 4.1 billion years, which is younger than the Moon itself.

In 2013, a paper published online in the journal Natural Geoscience, revealed that the Genesis Rock and other lunar anorthosites had large traces of water. The new research suggests that the early Moon was wet when it formed – this contradicts the predominant lunar formation theory that the Moon was formed from debris generated during a giant impact between Earth and another planetary body.


3. Nuvvuagittuq Greenstone Belt

Age: 4.28 billion years
Location: Hudson Bay, Quebec, Canada
Rock Type(s): “faux amphibolite”

Nuvvuagittuq Greenstone Belt photo source: Wikipedia

In 2001, geologists found the oldest known rocks on Earth, the Nuvvuagittuq greenstone belt, on the coast of the Hudson Bay in northern Quebec. Geologists dated the oldest parts of the rockbed to about 4.28 billion years ago, using ancient volcanic deposits, which they call “faux amphibolite”.

Since the rocks’ discovery, their age has been contested as different research has turned up different dates ranging between 3.7 billion – 4.37 billion years. A report published in March 2017 provides evidence that fossils of microorganisms have been found in the Nuvvuagittuq rocks, which would be the oldest trace of life yet discovered on Earth.


2. Jack Hills Zircon

Age: 4.375 billion years ± 6 million years
Location: Jack Hills, Australia
Rock Type(s): zircon

Nuvvuagittuq Greenstone Belt photo source: Live Science

The Jack Hills Zircon is believed to be the oldest geological material ever found on Earth, dating back to about 4.375 billion years, give or take 6 million years – the zircons are not technically rocks, but we felt that they should be included on this list.

Scientists published their findings in February 2014 in the journal of Natural Geoscience after analyzing single atoms of lead in a zircon crystal from Australia’s Jack Hill range. The trace elements found in the zircons suggest they came from water-rich, granite-like rocks such as granodiorite or tonalite. According to researchers, this information shows that “the earliest Earth was more like the Earth we know today”, which contrasts with earlier theories that said Earth was initially inhospitable.


1. Lunar Sample 67215

Age: 4.46 billion years
Location: from the Moon
Rock Type(s): Anorthosite

Lunar Sample 67215photo source: lpi.usra.edu

The oldest rock in the world is not from the Earth, but is a rock sample from the Moon, picked up during the Apollo 16 mission. The rock, only known as Lunar sample 67215 is an anorthosite believed to be about 4.46 billions years old. Analysis of the rock shows that it comes from a relatively shallow depth in the Moon’s crust, which sheds some light on how the initial lunar crust was formed – this information also provides insight into the formation of the terrestrial planets.

Researchers believe that the age of the rock show that the lunar anorthosites formed during the early history of the Moon, most likely by crystallization from a magma ocean.

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    1. The nature of the Black Stone has been much debated. It has been described variously as basalt stone, an agate, a piece of natural glass or—most popularly—a stony meteorite. Paul Partsch (de), the curator of the Austro-Hungarian imperial collection of minerals, published the first comprehensive analysis of the Black Stone in 1857 in which he favoured a meteoritic origin for the Stone. Robert Dietz and John McHone proposed in 1974 that the Black Stone was actually an agate, judging from its physical attributes and a report by an Arab geologist that the Stone contained clearly discernible diffusion banding characteristic of agates.

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