9.1" Marra Mamba Tigers Eye Slab - Mt. Brockman (2.7 Billion Years)
This specimen includes an acrylic display stand.
Western Australia. Only two deposits have ever produced “true” Marra Mamba, a rare type with reds, blues, yellow, gold and greens.
Marra Mamba Tiger's Eye formed around 2.7 billion years ago when stromatolites and other photosynthetic bacteria gave off oxygen as a waste product. This oxygen built up in the atmosphere and dissolved in the sea water. When iron, produced mainly from huge submarine volcanoes came in contact with this oxygen, it precipitated as iron oxide in the sea floor and resulted in iron-rich and silica-rich bands, which are now referred to as banded iron formations.
Geological movement over millions of years caused folding and faulting to occur, distortion the layers. Heated fluids passed through the rock and dissolved material and redeposited it elsewhere. The fibrous Riebeckite crystals were replaced by silica with fine dusts of yellow Goethite. These fibrous bands lead Tiger Eye to be classified as a chatoyant gemstone.
Causes of Color Banding: