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Azurite or Azure spar [5]: 14 is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite , after the type locality at Chessy-les-Mines near Lyon , France . [ 3 ]
Azurite was frequently used in European Renaissance painting. It appears, for example, in the dark blue sky of a Spanish altarpiece painting by Bartolome Bermejo. [8] In this painting, azurite is also combined with lead white to paint the green robe of the Saint. [8] During this time, azurite was a common pigment used to paint a blue sky. [1]
The next roughly billion years (1.85–0.85 Ga) are often referred to as the "Boring Billion" because little seemed to happen. The more oxidized layer of ocean water near the surface slowly deepened at the expense of the anoxic depths, but there did not seem to be any dramatic change in climate, biology or mineralogy. However, some of this ...
The deuterium to hydrogen ratio for ocean water on Earth is known very precisely to be (1.5576 ± 0.0005) × 10 −4. [35] This value represents a mixture of all of the sources that contributed to Earth's reservoirs, and is used to identify the source or sources of Earth's water.
Sediments and some trapped water are carried downwards by the slab and recycled into the deep mantle. [11] So far, Earth is the only planet where subduction is known to occur, and subduction zones are its most important tectonic feature. Subduction is the driving force behind plate tectonics, and without it, plate tectonics could not occur. [12]
Other blue minerals, such as the carbonate mineral, azurite, and the phosphate mineral, lazulite, may be confused with lazurite, but are easily distinguished with careful examination. At one time, lazurite was a synonym for azurite. [5]
The first eon in Earth's history, the Hadean, begins with the Earth's formation and is followed by the Archean eon at 3.8 Ga. [2]: 145 The oldest rocks found on Earth date to about 4.0 Ga, and the oldest detrital zircon crystals in rocks to about 4.4 Ga, [34] [35] [36] soon after the formation of the Earth's crust and the Earth itself.
The deep water cycle, or geologic water cycle, involves exchange of water with the mantle, with water carried down by subducting oceanic plates and returning through volcanic activity, distinct from the water cycle process that occurs above and on the surface of Earth. [1] Some of the water makes it all the way to the lower mantle and may even ...