Answer: Quartz

Petrified wood is the result of a special type of fossilization wherein, under the right conditions, ancient vegetation has transitioned from an organic state to an inorganic state–while retaining its shape–through the process of permineralization.

The process occurs when the organic materials, most often trees, become buried under sediment or volcanic ash. This process preserves the wood against immediate decay (aerobic decomposition) due to a lack of oxygen, but it is the subsequent process of mineral-laden water flowing through the sediment and ash that slowly deposits minerals into the plant’s cellular structure. Over time, in a slow but steady process, every organic bit of the specimen is replaced with a mineral counterpart.

The most common minerals involved in this process are in the silicate family and the vast majority of petrified wood artifacts are composed primarily of quartz. The wide variation in colors seen in the petrified plant matter we’ve recovered over the years is due to a huge array of contaminating elements in the water. Some common compounds (contaminants) and the coloration they provide are: carbon (black), copper (green/blue), and manganese (pink/orange).