Petrified wood, slice of Fossil Wood polished on both sides, edges are left rough. Size:21 cm x 23 cm x 2 cm weight 1.5 kg. Dark yellow, with brown/beige pattern in the middle. From tree-trunks dug up in East Java.
Very decorative object: can be used as a paperweight, or as something to place on the mantelpiece. Polished, but all growth rings are still visible.
Petrified wood is a type of
fossil: it consists of fossil wood where all the organic materials have
been replaced with minerals while retaining the original structure of
the wood. The petrifaction process occurs underground, when wood becomes
buried under sediment and is initially preserved due to a lack of
oxygen. Mineral-rich water flowing through the sediment deposits
minerals in the plant's cells and as the plant's lining and cellulose
decay away, a stone mould forms in its place.
Elements such as manganese, iron
and copper in the water/mud during the petrification process give
petrified wood a variety of color ranges. Pure quartz crystals are
colorless, but when contaminants are added to the process the crystals
take on a yellow, red or other tint.
Following is a list of minerals and related color hues:
Copper - green/blue
Cobalt - green/blue
Chromium - green/blue
Manganese - pink
Carbon - black
Iron Oxides - red, brown, yellow
Manganese Oxides - black
Silica - white, grey
Petrified Wood - Indonesia
Indonesia has the largest deposit of petrified wood in the world,
larger than Brazil, Arizona or even China. Indonesian Petrified Wood is
from ancient teak (hardwood) trees that turned to stone. The petrified
wood is from trees approximately 20 million years old. Minerals present
in the mud and water prior to and during the petrification process
leached into the wood giving it color.At
the end of the Tertiary era (Pliocene), a dense tropical forest, made
up of Dipterocarpus (of the Magnolia family) and of palm trees, covers
the Indonesian volcanic chain from Sumatra in Bali, to the west of Java.
From time to time, the volcanoes became active. The force of the
eruption was such that surrounding forests were uprooted. A thick layer
of burning volcanic ash covered them.The
nearest trees were consumed, those insufficiently covered rotted away.
But those between these two extremes benefited from ideal conditions.
They became naturally sterilised by the heat which destroyed bacteria
normally found in decay.
The
silica found in volcanic ash became dissolved in the percolation
fluids. It gradually replaced the wood, molecule after molecule, by
minerals such as quartz, agate or marble, hence preserving the shape of
the trees and even their cells. Petrified trees are sometimes found in
streams, but the most beautiful pieces are found buried several meters
deep.