As trees in ancient forests died they often fell into riverbeds or floodplains and were quickly buried under sediment or ash. Dissolved minerals being carried by groundwater then seeped into the organic matter filling any cavities. Once the water dried up the minerals left behind gradually crystallised as quartz.
The replacement of plant tissue with natural minerals in some petrified wood has been so precise the internal structure and external shape of the original log has been accurately reproduced. Petrified wood is unique and no two pieces are ever the same. This natural stone can date back more than 200 million years.
This petrified wood mineral has been lightly polished on the back but is highly polished on the front. There's a small section missing from the edge of the slice which can been seen in our photos if you look at the ten to twelve position. The section has been smoothed and polished so was clearly lost prior to the mineral being worked on. The third photo is the back of this slice.