Featured in this lot we have a collection of natural petrified wood with mineral deposit sites. The collection consists of four pieces of petrified wood each showing crystal formations and mineral deposits. Unlike other types of fossils which are typically impressions or compressions, petrified wood is a three-dimensional representation of the original organic material. The petrifaction process occurs underground, when wood becomes buried under sediment or volcanic ash and is initially preserved due to a lack of oxygen which inhibits aerobic decomposition. Mineral-laden water flowing through the covering material deposits minerals in the plant's cells; as the plant's decay, a stone mold forms in its place. The organic matter needs to become petrified before it decomposes completely. The process lasts millions of years. All the organic materials have been replaced with minerals while retaining the original structure of the limb. The largest of the pieces measures 7" tall by 5 1/2" wide and 4 1/2" thick with the smallest measuring 3 1/4" tall by 4 3/4" wide and 4" thick.