About the Stone Tiger Iron
Tiger Iron Often Confused for Tigers Eye
Tiger iron is a popular lapidary material often mistaken for the mineral tigers eye. Although the two share an almost identical colour and tigers eye is present in tiger iron, the two materials are not the same. In fact with closer inspection it's usually quite easy to tell one from the other.
Tiger iron is a banded iron formation but there's still some uncertainty about whether it can also be described as a stromatolite. This sedimentary rock contains an iron compound that can be extracted through smelting which is a process of heating and melting. BIF aka Banded Iron Formations formed beneath water over millions of years when layers of iron formed as a result of oxygen being released during the photosynthesis of blue green algae.
The following more detailed explanation comes from webmin.mindat.org/news/2009;
Banded Iron Formation (known to geologists as BIF) is a rock type consisting of repeated layers of the iron oxide minerals magnetite or hematite and shale or chert. The generally accepted concept of their formation is that the iron layers were formed in a marine environment as a result of oxygen being released during the photosynthetic process in blue green algae. The oxygen combined with dissolved iron to form insoluble iron oxides that precipitated to form a thin layer on the ocean floor which itself was composed of iron poor mud that eventually formed shale or chert. The banding is thought to result from cyclic variations in oxygen content of the water perhaps due to some sort of seasonal fluctuation.
The occurrence of banded iron formations is confined to a series of periods within the PreCambrian with some formations being as old as 3700 million years.
The most attractive type of tiger iron and material most often used for lapidary purposes is called jaspilite. This stone which takes on a high polish is made up of alternating layers of tigers eye which is a fibrous variety of quartz, red jasper and either the mineral hematite or magnetite. All of these materials are cryptocrystalline meaning their crystals are too small to be seen with the naked eye. Being made up of different minerals means that tiger iron is correctly classified as a rock not a mineral.
When used for the purpose of crystal healing tiger iron is said to promote inner strength and help balance emotional energies therefore helping to achieve peace, calmness and tranquillity in life. It encourages concentration, optimism and creativity and is also said to encourage an admiration for the pure and beautiful, especially for those of an artistic nature.
A relatively hard stone which grades 7 on Mohs scale of mineral hardness, tiger iron is widely used as a lapidary material particularly gemstones and is usually shaped as a cabochon.
The tiger iron in the photo at the top of this article is courtesy of James St. John. The photo is clickable and redirects to the original image. An entire album of images can be found here.
Our Collection of Tiger Iron