This curious mineral is polished on one side only. It exhibits a wonderful blend of colours. Due to the angle at which our photographs were taken it's not possible to fully appreciate the stone's vitreous lustre.
The formation of petrified wood began millions of years ago. When prehistoric trees fell many were quickly covered with sediment or volcanic ash.
Although initially preserved due to being starved of oxygen, some of the organic matter then began to decay. Any gaps were quickly replaced with minerals being carried in ground water. As the water dried up the minerals crystallised and hardened.
The process known as petrifaction is sometimes misunderstood. The crystallised minerals turned to stone, not the original organic matter. The reason why so much detail is often preserved in petrified wood is because in many cases the original cell structure remained largely intact.