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This is an artist's rendition of Earth's primordial environment and the beginnings of life.
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Earths Primordial Environment

In the beginning, Earth had a hydrogen based atmosphere, one which contained molecules in which hydrogen was a dominant constituent. Examples of such molecules include methane, CH4, hydrogen, H2, and ammonia, NH3. Such an atmosphere is also called reducing, as opposed to oxidizing. An oxidizing atmosphere is one that contains molecules with oxygen as the dominant constituent. Examples of those molecules include carbon dioxide, CO2, water vapor, H2O, and sulphur dioxide, SO2. In time, the early atmosphere of Earth evolved from a primitive reducing atmosphere to an oxidizing atmosphere.

Jupiter's atmosphere of today is an example of what all the primitive atmospheres must have been like. This is because, unlike smaller planets with less mass, Jupiter has such enormous gravity that very little of its original atmosphere has escaped.

Certain chemical reactions require energy to make them go (endogenic). That energy comes from ultraviolet (UV) light. Electricity in the form of lightning also serves that purpose. The Miller-Urey experiment showed that ultraviolet light plus lightning in a reducing atmosphere can produce long molecule chains which form the foundation of living cells. Earth's early environment was conducive to this process because the early atmosphere did not provide protection from ultraviolet light. Ultraviolet light can link small molecules together to make larger ones. (On the other hand, some forms of ultraviolet light can break apart large molecules).

On Earth today, the ozone layer, O3 absorbs almost all but the longest wavelengths of UV. On the early Earth, there was little free oxygen, so UV from the sun fell directly onto the surface of the Earth.

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The Fall 2010 issue of The Earth Scientist, focuses on rocks and minerals, including articles on minerals and mining, the use of minerals in society, and rare earth minerals, and includes 3 posters!

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Quartz is the second most common mineral in Earthís crust. It is a member of the quartz group, which includes less common minerals such as opal, crystobalite, and coesite. Silica (Si) and Oxygen (O) are...more

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Feldspar is the most common mineral in the Earthís crust, so you are very likely to find it in the rocks you collect! It is found it all of the three rock types, but is most common in intrusive igneous...more


Olivine looks like little green crystals. It is typically found in some igneous and metamorphic rocks. Often the crystals are so small that you need to use your hand lens or magnifying glass to see them...more

Type of Minerals

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF