Tiger iron is an attractive rock composed of alternating bands of tiger's eye, red jasper, black hematite and yellow limonite. The undulating, contrasting bands of color and luster make for an attractive motif. It's formation due to ancient, oxygen producing cyanobacteria over two billion years ago, though there is some debate about whether Tiger Iron should technically be considered a stromatolite itself.
Tiger iron is a stone composed mainly of tiger’s eye, red jasper and black hematite in an undulating banded pattern.
How Old Is Tiger Iron?
Tiger iron is found within banded iron formations, ranging from around 1.8 to 2.8 billion years old.
How Is Tiger Iron Formed?
Tiger iron was formed either directly or indirectly by ancient, oxygen producing cyanobacteria. Oxygen was not present in the early atmosphere, but arose as a byproduct of photosynthesis by cyanobacteria. This oxygen combined with dissolved iron in Earth's oceans to form insoluble iron oxides, which precipitated out, forming a thin layers on the ocean floor. The traditional view is that the bands in tiger iron represent cyclical variations in the oxygen levels in the oceans, possibly due to seasonal changes in the abundance of cyanobacteria. It’s also been proposed that these bands were formed more directly by the cyanobacteria as they were growing.
So, Is Tiger Iron A Stromatolite?
A stromatolite is a layered, trace fossil of ancient cyanobacteria. While it can be debated whether tiger iron should technically be considered a stromatolite, its formation is without a doubt due to these ancient, oxygen producing cyanobacteria.
Some have proposed that it’s a typical stromatolite that has undergone mineral replacement with iron oxides. It’s also been proposed that these microbes formed the banded iron directly while the stromatolite was being formed. The more conventional view is the banding tiger iron represents cyclical changes in ocean oxygen levels due to changes in the abundance (seasonal?) of these cyanobacteria.
Where Is Tiger Iron Found?
Nearly all of the tiger iron commercially available is mined from the massive, banded iron formations in the Ord Ranges of Western Australia.
What Is Tiger Iron Used For?
Tiger iron is often polished and used for decorative purposes due to its beautiful, banded patterning.
Washington state has now joined over a dozen other states to put in place “shelter in place” or “stay at home” orders. While we agree this is the correct course of action, it will have a substantial impact on our business. It effectively shuts down much of our company for several weeks.
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