The Private Palaeobotanical Laboratory of Fossil Wood operates since 2005 in Warsaw, Poland. In 2008 a terrain branch of the Laboratory was established in Twardogora.

Its activities are focused on:

– the study of fossil remains of woody plants, especially wood, including to identify taxonomic affiliation,

– gaining and gathering research materials of fossilized flora,

– searching for the fossils in a premises.





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1. Stereoscopic optical microscope

Anatomical details visible in cross sections of petrified wood (photographed by Sandra)


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2. Scanning electron microscope

Photographed by:
Prof. Dr. Zbigniew Laurow, Warsaw Agricultural University (SGGW),
Dr. Tadeusz Narojek, Warsaw Agricultural University (SGGW).


Submicroscope structures in petrified wood

Submicroscope structures in living tree

Radial longitudinal section

Submicroscope structures in petrified wood

Submicroscope structures in living Pinus

Amber in petrified wood

Resin canal

Spawn of fungi in petrified wood

Spawn of fungi in living tree

Chalcedony in petrified wood

Quartz in petrified wood

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3. Computed tomography scanner

Photographed by:
Prof. Dr. Zbigniew Laurow, Warsaw Agricultural University (SGGW),
Dr. Tadeusz Narojek, Warsaw Agricultural University (SGGW).


Petrified wood from Kotlina Klodzka, Poland, without visible traces of insects and tomograph of the same wood with good visible tunnels

Living Pinus with insects feeding ground

Feeding ground of Coleoptera (probably Cerambycidae family) in petrified wood

Feeding ground of Arhopalus rusticus in living Pinus

Feeding ground of Hymenoptera (probably Siricidae family) in petrified wood

Feeding ground of Hymenoptera (probably Formicidae family) in petrified wood

Feeding ground of Camponotus herculeanus in living tree

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4. Occurrence and age of petrified wood

Find and collectible today petrified wood comes from different geological eras and represent a variety of plant species. Is found on all continents.

Some of the locations are vast areas of forest remains – sometimes even trunks buried in the position of growth. Others, just small – in comparison to the previous – occurrences of fossils applied in secondary deposits.

Remains of several dozen meters trunks of woody plants are found, as well as fragments of few centimeters. Some of them can boast of "knowledge" of the dinosaurs, but the oldest are from Morocco (Hamar Laghdad), the Givetian (Middle Devonian) and dating back around 380–372 million years old, while some of the latest remains of petrified wood dates back to the Middle Pleistocene – are known from the province Tak in Thailand, and the location Dunarobba in Italy (these are about 40 thousand years).

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5. Identifying of petrified wood

Fossils of wood can be successfully identified. Often visible to the naked eye are figures of annual growth rings, rays and wood knots. However, in order to determine the position of the generic or species, microscopic observation of anatomical structures is necessary.

Minerally fixed structures, for example, vessels, tracheids, vascular bundles, resin canals, leads to the identification of diagnostic features of wood, and thus to the species identification.

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6. Minerals and singularities occurring in petrified wood

Some exhibits of petrified wood, in addition to species diversity, deserve special attention because of the minerals present in them and the peculiar characteristics. For example, look spectacular specimens with agate, or those with quartz crystals crystallized on the surface, which are also sometimes in the interior of the specimen, or even forming in the small geodes.

In silicified wood the presence of minerals not belonging to the group of silica, such as, for example, pyrite, calcite or fluorite, is less common.

The distinguishing features of the species are observed in the petrified wood singularities. For example, traces of wood invading organisms and coprolites (fossilized excrements) of organisms feeding on wood, or inhabiting wood.

Very unique are specimens showing radioactive or phosphorescence.

Examples of petrified wood with the outlined features are shown below.


Opal


Chalcedony


Fluorite

Fern roots in the wood core

Coprolites

Shells of molluscs

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7. Wood petrifying factors

The most common remains of petrified wood were formed by the silicification process, in which the petrifying substance is silica.

Silica gel (H4SiO4) fossilising plant tissues may pass in consecutive varieties:
– opal,
– chalcedony (including, for example agate),
– quarc.
Other, less common wood petryfying factors can be (P. Buurman 1972):
– apatite,
– calcium carbonates (calcite, aragonite), magnesium, iron (siderite),
– iron sulfides (pyrite, marcasite), zinc,
– iron oxides (goethite, hematite).

Examples of wood mineralized by the varieties of silica and iron oxides, fluorite and pyrite are shown below.


Opal


Opal


Opal


Agate


Agate


Agate


Fluorite


Pyrite


Iron oxides


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8. Colors of petrified wood

The variety of petrified wood colors is not due to wood color of living plants and its species, but is dependent on the presence of minerals that penetrate the silica which mineralized remains. Thanks to minerals colorless quartz gains hue. The perpetrators of the occurrence of colors in the petrified wood can be:

– chrome – green, blue,

– cobalt – green, blue,

– silica – white, gray,

– manganese – pink,

– copper – green, blue,

– manganese oxide – black, blue, purple,

– iron oxide – red, brown, orange, yellow,

– coal – black.

In the Gallery there are showed many specimens of unusual color palette.

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Photographs of scanning electron microscopy and tomograms received the courtesy of Professor Zbigniew Laurow.

Sandra Niemirowska