Petrified wood "Araucarite" – Madagascar

Petrified wood, often called Araucarite, is a fossilized form of wood where the organic material has been replaced by minerals, primarily quartz, while preserving the original structure of the wood. This process takes millions of years and results in a beautifully coloured stone that preserves the details of the original wood. The name Araucarite comes from Araucaria, one of the most common tree species found in this fossilized form. Araucaria is a genus of trees belonging to the group of conifers that were abundant in prehistoric times, especially during the Triassic and Jurassic periods.

The geological process

Fossilization: the process begins when a tree falls and is quickly buried under sediments that protect it from decomposition. Mineral-rich waters percolate through the wood and silicate minerals (such as quartz, chalcedony or opal) gradually replace the organic material. This process is known as permineralization.

Fossilization takes approximately 20 to 200 million years, which means that most petrified wood is very old, often dating back to the Permian, Carboniferous or Jurassic periods.

Locality

Petrified wood in Madagascar is most commonly found in the Atsimo-Andrefana region in the southwest of the island, particularly around the town of Mahajanga and Isalo National Park. The region is known for its extensive fossil fields, which contain numerous specimens of petrified wood.

Colour

Madagascar's petrified wood is renowned for its beautiful and varied colours, which include shades of red, brown, yellow, orange, blue and black. These colours are the result of the presence of various minerals:

• Iron oxides: They add red, brown and yellow hues.
• Manganese: Contributes to the black and blue colors.
• Quartz: Adds luster and durability, often in the form of transparent or milky areas.

Texture

Petrified wood retains the original texture of the wood, including the year rings, which can be very visible. This detailed texture allows scientists to study growth patterns and climatic conditions at the time the tree lived.

Curiosities

Entire fossil forests can be found in Madagascar where tree trunks are preserved in their original position, providing a unique view of prehistoric ecosystems.

Araucarite dates back to the time when dinosaurs walked the Earth, making it a witness to one of the most fascinating eras of our planetary history.