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article imageEssential Science: World's oldest colors discovered

By Tim Sandle     Jul 23, 2018 in Science
Geologists have discovered the world's oldest colors, by examining some of the oldest rocks on Earth. The rocks were isolated from North Africa, and pigments were then extracted.
Researchers from the Australian National University have been examining some of the oldest rocks and from this they have found the oldest colors in the geological record. These are 1.1-billion-year-old bright pink pigments. The researchers extracted the pigments from the ancient rocks, recovering the samples from deep beneath the Sahara desert in Africa.
Black shale rock
According to lead researcher Dr. Nur Gueneli, the pigments were taken from marine black shales of the Taoudeni Basin in Mauritania, West Africa. Black shale, also called Carboniferous Shale, variety of shale that contains abundant organic matter, pyrite and sometimes carbonate nodules or layers and, in some locations, concentrations of copper, nickel, uranium and vanadium.
Standard shale is a fine-grained, clastic sedimentary rock ('clastic' is a term denoting rocks composed of broken pieces of older rocks). For industry, black shales are being examined due to their oil and gas potential. In addition, the rock can contain rich deposits of cobalt, chromium, molybdenum, nickel, platinum group elements, rhenium, and vanadium.
Taoudeni Basin
The Taoudeni Basin is a major geological formation in West Africa named after the Taoudenni village in northern Mali. The Taoudeni is the largest sedimentary basin in Northwest Africa, and it was formed during the mid-late Proterozoic era (representing the time just before the proliferation of complex life on Earth).
New discovery
What is remarkable about the new pigments is that they are more than half a billion years older than any previous pigment discoveries. According to Gueneli: "The bright pink pigments are the molecular fossils of chlorophyll that were produced by ancient photosynthetic organisms inhabiting an ancient ocean that has long since vanished."
In their concentrated form, the fossil pigments range from blood red to deep purple in their concentrated form. However, each reverts to a bright pink once diluted. The origin of the pigments are bacterial. At one time, cyanobacteria dominated the base of the food chain in the oceans. These are a phylum of bacteria that obtain their energy through photosynthesis.
The findings provide further information about the development of our planet and the formation of life. The geological research has been published in the journal PNAS. The research paper is titled "1.1-billion-year-old porphyrins establish a marine ecosystem dominated by bacterial primary producers."
Essential Science
This article is part of Digital Journal's regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue. Last week we considered a new study that suggests that living in greener neighborhoods with access to open spaces, is associated with slower cognitive decline in relation to the elderly.
The week before we considered just how big the periodic table could potentially become. This was in relation to most recent four elements incorporated: nihonium, moscovium, tennessine, and oganesson.
More about Color, pigment, Minerals, Rocks, Earth
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