LARGE MARRA MAMBA TIGER'S - EYE SLAB. ...

Description

LARGE MARRA MAMBA TIGER'S - EYE SLAB
Paleoproterozoic
Mt Brockman Station, Western Australia
The incredible Marra Mamba tiger eye is found only in a small area, Western Australia, and represents one of the finest and rarest of the world's minerals. Tiger eye is an ancient rock, formed from sediments laid down at the bottom of a shallow sea over two and a half billion years ago when the early Earth's atmosphere had little or no oxygen. Sometime later (approximately 2,700 million years ago) the first photosynthetic bacteria evolved and began to give off oxygen as a waste product, which built up in the atmosphere and dissolved in sea water. When this came in contact with iron (produced mainly from huge submarine volcanoes), it precipitated as iron oxide in the sea floor mud and resulted in iron rich bands and silica rich bands now classified as a banded iron formation (or BIF). Other minerals were also present and heating and burial brought about the crystallization of layers; it seems likely that solutions carrying sodium penetrated along some of these layers and this is where the mineral riebeckite was formed. The fibrous riebeckite variation with which Tiger eye originates is known as crocidolite, or blue asbestos, but pseudomorphically replaced by silica, with a fine dust of yellow goethite outlining the shape of the original crystals; this is the same way in which fossil wood preserves the outline of cells and growth rings. It seems hardly possible that the colors and patterns on this slab are a natural occurrence, but millions of years' of tectonic and mineralogical activity has produced Nature's finest abstract artwork. The colors flow into one another like indissoluble oil paints creating a wonderful "waterfall" effect that is fascinating to behold, dominated by a strong olive green and a gorgeous warm metallic gold band of Tiger's - eye. Left with a naturally contoured edge, this large and beautiful slab measures 68 x 21¾ x 1 inches and is stabilized with an aluminum backing.

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