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Article: Greenstone.(Word to the Wise)
- Article from:
- Rocks & Minerals
- Article date:
- November 1, 2008
- Author:
CopyrightCOPYRIGHT 2008 Heldref Publications. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Iron is the most abundant chromophore (an element that imparts color to a mineral by its presence in the structure) in the earth. When iron is in its divalent oxidation state ([Fe.sup.2+]), as is found in such minerals as olivine, pyroxenes, amphiboles, chlorites, and epidote, it typically imparts a green color. Exceptions to this do exist and include, for example, almandine, which is colored red by the presence of divalent iron.
Acting as does pigmentation in paint, [Fe.sup.2+]-bearing minerals, even as minor constituents in a rock, can impart a distinct green color, especially when fine grained and highly dispersed. Although many minerals and rocks are green ...