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2.55" Marra Mamba (Packsaddle) Jasper Sphere - Mt. Brockman
This is a 2.55" wide polished sphere of Marra Mamba jasper (packsaddle jasper) from Mt. Brockman in Western Australia. This specimen is just about 2.7 billion years old! It has been polished to a glossy finish all the way around.
About Marra Mamba Tiger's Eye
Marra Mamba Tiger's Eye is a rare type of Tiger's Eye found only in the Hamersley Ranges of Western Australia. Only two deposits have ever produced “true” Marra Mamba, a rare type with reds, blues, yellows, golds 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 into sea water. When iron, produced mainly from huge submarine volcanoes, came in contact with this oxygen, it precipitated as iron oxide onto the sea floor and resulted in alternating iron-rich and silica-rich bands, which are now referred to as banded iron formations found in the mineral. These iron bands are often magnetic!
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. Crocidolite, the fibrous form of riebeckite interspersed with the iron bands, was replaced by silica with fine dusts of yellow goethite and other iron-rich minerals. These fibrous bands create the chatoyant effect that gives tiger's eye its classification as a chatoyant gemstone.
Causes of Color Banding:
White - Quartz
Yellow - Goethite
Red - Hematite
Blue - Riebeckite (unreplaced by silica)
Green - A mixture of blue Riebeckite and yellow goethite
Black -Hematite and Magnetite
Marra Mamba Tiger's Eye is a rare type of Tiger's Eye found only in the Hamersley Ranges of Western Australia. Only two deposits have ever produced “true” Marra Mamba, a rare type with reds, blues, yellows, golds 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 into sea water. When iron, produced mainly from huge submarine volcanoes, came in contact with this oxygen, it precipitated as iron oxide onto the sea floor and resulted in alternating iron-rich and silica-rich bands, which are now referred to as banded iron formations found in the mineral. These iron bands are often magnetic!
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. Crocidolite, the fibrous form of riebeckite interspersed with the iron bands, was replaced by silica with fine dusts of yellow goethite and other iron-rich minerals. These fibrous bands create the chatoyant effect that gives tiger's eye its classification as a chatoyant gemstone.
Causes of Color Banding:
SPECIES
Chalcedony var. Jasper & Iron
LOCATION
Mt. Brockman, Western Australia
SIZE
2.55" diameter
CATEGORY
SUB CATEGORY
ITEM
#309178
