The Pilbara Craton is an ancient and stable part of the Earth's crust found in the Pilbara region of Western Australia.

It is one of only two well-preserved pieces of Earth's crust from the Archaean time period, which lasted between 3.8 and 2.7 billion years ago. The other is the Kaapvaal Craton in South Africa. The youngest rocks in the Pilbara Craton area are about 1.7 billion years old. These two regions may have once been part of the Vaalbara supercontinent or the continent of Ur.

There are two ways to classify the area into smaller regions:

Geology

The most important part of the Pilbara Craton for studying Earth's early crust is known as the Eastern Pilbara Craton. This area still shows crustal rocks that are up to 3.8 billion years old, along with granitic rock formations and greenstone belts that are about 3.5 to 3.2 billion years old. In 2007, geologists revised their understanding of the Pilbara Craton by separating a thick layer of alternating sedimentary and volcanic rocks that form the Fortescue, Hamersley, and Turee Creek basins. These basins are typically dated to be between 2.78 and 2.42 billion years old. A younger volcanic and sedimentary basin called the Ashburton Basin is dated to be between 2.21 and 1.79 billion years old. A surface area between the Fortescue and Hamersley basins is even younger, less than 1.7 billion years old, as are the surrounding surface rocks near the Pilbara Craton. To the east and south of the Eastern Pilbara Craton, there are large areas of very old rocks. These rocks are limited to the traditional Pilbara Craton area, which is believed to be mostly hidden underground.

In 2025, scientists discovered shatter cones near Marble Bar, confirming that the 3.47 billion-year-old North Pole Dome is the oldest known impact structure in the world.

The Pilbara region contains large deposits of high-quality iron ore, as well as valuable minerals such as gold, silver, copper, nickel, lead, zinc, molybdenum, vanadium, and fluorite.

Evidence of earliest life

Evidence of the earliest known life on land may have been found in 3.48-billion-year-old geyserite and other minerals found near hot springs and geysers in the Dresser Formation in the Pilbara Craton. Structures formed by living organisms, such as stromatolites and MISS, were found in areas that were once tidal, lagoonal, or coastal environments. These environments can be understood by studying the layers of rock in the Dresser Formation. The rocks also show signs of hematite changes that may have been influenced by microbes.

The earliest direct evidence of life on Earth may be fossils of tiny organisms found in 3.465-billion-year-old Australian Apex chert rocks. However, scientists have debated whether these structures were formed by living things. At first, 11 types of microorganisms were thought to exist in a deposit that appeared to be near a river because of certain features, like rounded and sorted grains. Later studies showed that the area where the fossils were found was actually a hydrothermal environment, which is now widely accepted. Many scientists have suggested that the long, thread-like structures found in the rocks could have formed without living organisms. These structures include carbon-rich layers around quartz spheres, witherite shapes, and hematite-filled cracks. Tests using Raman spectroscopy on the carbon in the structures have given mixed results, so many scientists believe this method alone cannot confirm if the structures are biological. The strongest evidence so far comes from detailed electron microscopy, which shows that the tiny shapes and carbon distribution in the structures are unlikely to have come from living organisms. Instead, the structures may have formed due to hydrothermal processes that altered potassium micas, allowing barium, iron, and carbonate to attach to them later.

Carbon-rich structures that look like they could be from living organisms have also been found in the 3.47-billion-year-old Mount Ada Basalt, which is slightly older than the Apex chert. However, scientists have also debated whether these structures were formed by living things or by non-living processes.

Other possible signs of early life from the Precambrian period have been found in the northeastern Pilbara Craton, including tiny carbon-rich fossils.