Large piece of petrified / fossilised palm wood
Here's an unusual thing, particularly in the UK. This is a large piece of silicified petrified palm wood. This one is also unusual as unlike many of the pieces that are from species in the United States, this one was found in the Sahara desert about 40 years ago.
Fossilized palm wood is also known as Palmoxylon. It is an extinct genus of palm found around the world. These plants lived from the Late Cretaceous (83 million years ago) until the early Miocene (34 million years ago). The fossilization process involves the replacement of organic wood cells by silicate minerals over time. The spotted look of palmwood is caused by fossilized rod-like structures within the original wood. Depending upon the angle the stone is cut, they show up at spots, tapering rods, or lines. These are used widely in jewelry making as the cut and polished faces are striking.
This is a big piece measuring approximately 14cm x 15cm x 11cm and weighing in at a whopping 2.8kg.