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Rutile Goethite Calcite |
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Spot E is a brownish material abundant in this rock section while
spot D is a dark red-brown crystal of a minor mineral. A higher
magnification image is reproduced below. |
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| Higher magnification image showing
the color difference between both crystals D and E. |
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| Raman spectrum of spot D
indicates clearly the presence of Rutile. Rutile and Ilmenite
detected previously confirm the presence of titanium in this rock. |
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| The structure of the brownish material (
spot E) is elucidated by the Raman spectrum: it is made up of Calcite
and Goethite. The detailed structure of this two minerals
assemblage is illustrated in the thin section images below. |
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| Enlarged (10X objective) thin section image
showing a high interference color calcite material (pink or green
depending on polarization vector) with embedded goethite veins.
Depending on the precise position of the laser spot, calcite alone or a
mixed spectrum of calcite and goethite can be obtained. The
section shows also the low birefringence albite crystals and some highly
colored muscovite. |
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| Same view without analyzer inserted. The
Goethite network is clearly visible. |
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| Another part of the thin section
with the green-pink carbonate with goethite inserted in the fractures of
the grains. |
