Petrification Jen Cowman

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  • Jen Cowman

  • Sakinah Alhabshi

  • CEE 367

  • Spring 2003

What is Petrification?

  • The replacement of the normal cells of organic matter with other minerals

  • According to evolutionary doctrine, petrification requires much time, usually millions of years, but how much time is really needed in this process?

  • Things are usually petrified in soil or by a water source with a high mineral content

  • Affected by – temperature, pressure, minerals

Mother Shipton’s Petrifying Well


  • Available for public viewing since 1630 – cascades from River Nidd & forms an aqueous curtain to Mother Shipton’s Cave

  • High mineral content:

    • calcium, sodium and magnesium
    • traces of lead, zinc, iron, manganese and aluminium
  • Exist mainly as sulphates and carbonates, with some chlorides and a trace of silica

  • Proportions have remained more or less regular over many years


  • As dissolved calcite (CaCO3) is exposed to air, CO2 escapes and the limestone is deposited

    • 2HCO3- + Ca2+  CO2(g) + CaCO3(s) + H2O
  • Petrifies sponges/teddy-bears: 4-6 months, Animals: 12-18 months

  • Flow of 700 gal/hr

Making a Profit?


  • Tufa – soft rock

  • Travertine – hard rock

  • Dark/light bands

  • The face of the rock has to be scoured every 6 weeks to prevent it from getting top heavy and falling over

Petrified Forest National Park


  • The dead wood needs to be protected from decay

  • The dead wood becomes saturated with mineral-laden water

  • The porous nature of wood allows the movement of water-borne particles

  • The water itself needs to harbor specific minerals necessary for petrification


  • After burial and saturation, chemical reactions take place between the minerals and the cellulose compounds in the cell walls

  • Mineral crystals grow in the spaces left behind by the dissolution of the cell walls

  • Two phases of crystal deposition result in complete mineral replacement of the wood


  • Minerals - iron, manganese, carbon, and chromium, cause the colors of the petrified wood

  • Red – iron

  • Green – chromium

  • Black – carbon / magnetite

Yellowstone National Park

  • Continental “hot spot” in Wyoming

  • Mammoth Hot Spring Terraces

    • 100 hot springs scattered over terraces
    • Thermal springs deposit CaCO3 as travertine between 2.8 – 56.5 cm/year
    • Silica deposition rates into blocks of wood in alkaline springs at Yellowstone between 0.1 and 4.0 mm/yr

Liberty Cap

  • Liberty Cap

    • 45 ft tall
    • Cone formed from a steady flow of hot water from a single source
    • Presently inactive

Opal Terrace

  • Opal Terrace

    • 160° F
    • Known for its pastel colors
    • A tennis court had to be removed because it grew too quickly

New Highland Terrace

  • Terracette

  • Hot water flows over the lip and forms stalactites

“Instant” Petrified Woods

  • Advanced Ceramic Labs at the University of Washington, Seattle

  • Wood-ceramic composites 20–120% harder than regular wood

  • Simple process – soak wood in silicon and aluminium solution, then oven-cure at 44°C (112°F)

  • Hamilton Hicks, Connecticut – made a chemical 'cocktail' of sodium silicate, natural spring or volcanic mineral water - high content of calcium, magnesium, manganese and other metal salts, and citric or malic acid

Potential Uses for “Instant” Petrified Woods

  • Fireproofing wooden structure

  • Longer-wearing floors and furniture

  • Greater strength wood

  • Insect, decay and salt-water proof wood in buildings


  • Misconception: fossilized wood buried in rock strata must have taken thousands, if not millions, of years to petrify

  • Can be rapid

  • Good knowledge base – we can make petrified wood for our benefit

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