Petrified wood

Physical Featuhttp

1. Color- Brown, gray, red, yellow.

2. Streak- White.

3. Luster- Waxy, vitreous, dull.

4. Cleavage- None.

5. Transparency- Transparent to opaque.

6. Fracture- Conchoidal.

7. Hardness- 7.

How does a tree become petrified? About 200 million year's ago when the dinosaurs roamed the earth, large tree's somewhat like the modern day conifer's grew abundant. As the tree's aged and died off, they fell to the ground to lay. Eventually the tree's were swept away by raging flood water's, river's, and lake's. Many of these tree's decomposed quickly, but for others, they were buried deep into massive amounts of oxygen free sediments. The lack of oxygen in the sediments causes the decaying process to slow. The sediment covering the tree's is rich in silica, and volcanic ash, and over a period of time the minerals began to dissolve in the water that seeped through the sediment. This allows the mineral's to absorb within the porous wood. After thousands of years crystalization starts forming in the cellular structure replacing the organic material with Quartz, chalcedony, and jasper. This is called petrification, even today we cannot fully understand the process of fossilization of tree's. Petrified wood's coloring comes from the impurities present in the wood during fossilization, some of these impurities may be caused by manganese ,iron, lithium, and copper. Petrified wood is considered pseudomorph. Pseudomorphs are minerals which change in their chemical composition, but remain in their original state. One of the largest deposits of petrified wood is found at Arizona's Petrified Forest National Park.