Silicified wood is a fossil tree stump whose trunk was buried underground and completely turned into silica, keeping its original shape. It is an important material in studying paleoecology, paleogeography and paleoclimatology.

The Hyanggyogol Silicified Wood is a natural monument which is found on a mountain slope in Hyanggyo Valley, Kilju County Township, North Hamgyong Province in the northern part of Korea. The silicified wood is 3 metres high and 40 to 50 centimetres across.

It has characteristics of pine and nut pine family. The section has black, deep yellow and white annual rings and bark structures are clear on the surface.

The Hyanggyogol Silicified Wood makes it possible to guess the distribution of plants which were thick on the earth about 18 million years ago and shows that those plants in the forest were the origin of coal.