|
What is petrified wood?
Petrified wood has been preserved for millions of years by the
process of petrification. This process turns the wood into
stone. Even though petrified wood is fragile, it is also harder
than steel. Petrified wood is much heavier than the original
log, weighing as much as 150 - 200 pounds per cubic foot.
 In
order for wood to become petrified, it has to have been encased
with volcanic ash, volcanic mud flows, sediments in lakes and
swamps or material washed in by violent floods - by any means
which would exclude oxygen and thus prevent decay.
A number of mineral substances (such as calcite, pyrite,
marcasite) can cause wood to petrify, but by far the most common
is silica. Solutions of silica dissolved in ground water
infiltrate the buried wood and through a complex chemical
process are precipitated and left in the individual plant cells.
Here the silica may take a variety of forms, such as agate,
jasper, chalcedony or opal.
 The
beautiful and varied colors of fossil wood are caused by the
presence of other minerals that enter the wood in solution with
the silica. When the end result is white or gray in hue, pure
silica was more than likely present during the petrification
process. If iron oxides are included in the
silica the wood becomes stained with a yellow or reddish brown
tint. If copper, cobalt or chromium was present, the petrified
wood will be tinted with greens and/or blues. Manganese will
create a pink coloration, while carbon blackens the petrified
wood.
|
