Jaspilite / Banded Iron Formation

Jaspilite or banded iron formation, is layers of red jasper and hematite.  You may see this same type of rock under a wide variety of names, each one claiming to be unique to the locality where it was collected.  However, banded iron formations formed world wide billions of years ago, during the Precambrian – before multi-cellular lifeforms existed and long before life on land existed.  The jasper or chert forms as tiny micro-organisms in the ocean (diatoms) died and fell to the bottom of the ocean.  Their silica-rich shells accumulated and compacted, forming the jasper or chert.  The hematite is related to iron deposits that were extruded from hydrothermal vents on the ocean floor (in the case of the silver-gray specular hematite).

A second way that banded iron formations are thought to form is seasonal.  The chert layers are still from the diatoms accumulating.  But, during the rainy season, the barren soil, devoid of any plant material to hold it in place, would get washed into the ocean and accumulate as red hematite layers.

Banded iron formations only are found in rocks that are older than 750 million years, with most of them forming between 2.4-1.8 billion years ago.  Their formation is related to the occurrence of stromatolites, which form kambaba jasper.  The stromatolites produced oxygen that oxidized the iron.  When oxygen-using animals appeared, the amount of free oxygen in the atmosphere was depleted and banded iron formations stopped forming.

Jaspilite is an ancient stone, attesting to the strength of time.  The combination of jasper and hematite are thought to aid in decreasing negative energy, decrease stress and help with courage.

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