Tiger Iron | Banded Iron Formation (BIF)
Tiger iron is a natural stone often mistaken for the mineral tigers eye. Although the two materials can share an almost identical colour and tigers eye is present in tiger iron, they are not the same stone. Even where the two materials look very similar with closer inspection it's usually quite easy to tell one from the other.
Tiger iron is a banded iron formation (BIF) 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. 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 came from webmin.mindat.org/news/2009 although the page no longer seems to exist;
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 decorative 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 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.
Tiger iron is a relatively hard stone which grades 7 on Mohs scale of mineral hardness.
Tiger Iron Healing Properties
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 encourages an admiration for the pure and beautiful. It's especially suited to those with an artistic nature.
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 full size image. An entire album of tiger iron images can be found here. The "banded iron formaton (BIF)" link in second paragraph redirects to an amazing photo by Roberto Bosi.
Our Collection of Tiger Iron