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Figure 5.7. Thin section of experimentally blackened soilstone crust (one-half hour at 400°C). Crude laminations of originally reddish-brown cryptocrystalline calcite (color imparted mainly by organic matter) turned black, while less darkly stained portions between dark laminae only turned grey. In hand specimen, as shown in Figure 5.5C, the rock looks completely black. A thin section photo of unheated crust (control) is not shown because in black-and-white photography no differences could be seen (plain light). Scale bar 400 µm.

Return to: Field Observations and Some Experimental Results | Discussion

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Last updated: 09 December, 2004 @ 01:23 PM(TJE)