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    Atmospheric CO2 Level Tops 400 ppm

    During the week of May 13th, the CO2 level at the Mauna Loa Observatory in Hawaii topped 400 ppm repeatedly. Daily levels of CO2 can vary due to weather, and there are seasonal trends as well. The level of atmospheric greenhouse gases continues to increase, now over 120 ppm since the Industrial Revolution began. For more on the Keeling Curve, see http://keelingcurve.ucsd.edu/. Find out more about greenhouse gases and warming.
Hematite
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Hematite

A sample of hematite may look like little more than a dark gray blob. That might seem impossible to identify but with a streak test, you can easily identify it! To tell if it is hematite, just rub the mineral against a white streak plate and it will form a small amount of red powder!

The largest amounts of hematite are found in sedimentary rocks that formed from weathering iron-rich minerals. In these sedimentary deposits, hematite is thought to have precipitated from lakes or seas by organic and/or chemical processes. The hematite often occurs with intermixed layers of quartz or chert.

Hematite is an important ore of iron. It is also used as a pigment in paint and in polishing compounds. It is made into a variety of handcrafted objects such as beads and jewelry.

  • Shape: Trigonal (commonly occurs as tabular crystals)
  • Luster: Metallic to sub-metalic to dull
  • Color: Reddish-brown, gray to black
  • Streak: Red
  • Hardness: 5.5 to 6.5 on Mohs Hardness Scale
  • Cleavage: None
  • Fracture: Conchoidal

Last modified April 25, 2003 by Lisa Gardiner.

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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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