MINERAL OF THE MONTH
July 2007: Labadorite
Labradorite
This month’s mineral of the month is Labradorite, which was first discovered in the Labrador Peninsula in Canada. It is also found in Norway, Finland, and Russia. It is truly a captivating mineral that displays a colorful shiller effect when held and moved during observation. The color display is from layers of intergrowth inside the crystal. These intergrowth layers are caused from compatible chemistries at high temperature becoming incompatible at lower temperature that results in a separating and layering of the crystal components. The color effect is caused when light enters the specimen, only to be refracted back and forth by the deeper layers. The refracted light is slowed as it travels through the layers and mixes with other light rays to change and produce a different wavelength of light. The color effect depends on the thickness and orientation of the layers.
Labradorite is a member of the plagioclase series of minerals, which comprises feldspars. It contains sodium, calcium, aluminum, silicon, and oxygen. The color is gray to smoky black. It has a dull to vitreous luster. The crystals are transparent to translucent. It has a conchoidal fracture pattern, a hardness of between 6 and 6.5, and a specific gravity of between 2.70 and 2.74. The flashes of color (labradorescence) can vary between blue, violet, green and sometimes orange and yellow.
Mineral of the Month Archives
May 2007 Rainbow Fluorite
June 2007 Lake Superior Michipicoten Agate
July 2007 Labadorite
August 2007 Rain Flower Agate
Fall 2007 Malachite
December 2007 Nepheline Syenite
January 2008 Native Copper
February 2008 Amazonite
March 2008 Lake Superior Agate
April 2008 Shadow Agate
May 2008 Apohpylite
June 2008 Ocean Jasper
Summer 2008 Marra Mamba Tiger's Eye
September 2008 Mohawkite
October 2008 Mexican opal
November 2008 Prehnite
December 2008 Picture Jasper
January 2009 Sea Shell Jasper
February 2009 Polychrome Jasper
March 2009 Selenite Desert Rose
Spring 2009 Coyamito Agate
July 2009 Obsidian Needles
August 2009 Goethite
September 2009 Banded Iron Formation
Fall 2009 Fairburn Agate
February 2010 Kentucky Agate
March 2010 Fossilized Dinosaur Bone
April/May 2010 Kentucky Agate
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Gitche Gumee Museum.
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