A Geoscience Digital Image Library

TitlePetrified Wood
DescriptionPetrified wood in general must be buried before it can be preserved. At some point after the initial burial, it must be over laden with silica rich volcanic “ash” to become silicified. The silica that fills the molds is usually dissolved in water. The water which contains the dissolved silica is usually hot. For some reason the dissolved silica in the water precipitates or is left in the mold, attaching itself to the lignun and cellulose of the wood ( if it is still there). First it dehydrates into silica gel. Then after a short period of time it dehydrates further and hardens into opal. Finally after a much longer period of time it dehydrates further and hardens into chert or cryptocrystaline quartz. Jasper and agate are examples of other forms of microcrystaline or cryptocrystaline quartz.
LocationUSA ▹ Utah ▹ Millard
PhotographerShannon Heinle. 2001-06-05.
CollectionUniversity of North Dakota Mineralogy Collection #1565.
Key wordspetrified wood, opal, chert, jasper, agate
Tech details357 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens.
GeoDIL number607