Figure 3-6. Coating of smectite (S) on aragonite (A) in a stalagmite from Carlsbad Caverns. Arrow points to edge of smectite coating. Energy dispersive X-ray analysis indicates presence of Si and Mg in arrowed material labeled "S". The uniform thickness of the smectite coating and the uniform orientation of particles at its edge suggests that it precipitated chemically on this surface and is not a detrital deposit. The atlas has another image of smectite in this stalagmite. Scanning electron microscope secondary electron image generated with a 15 keV acccelerating voltage; white scale bar at lower right is 1 micron long. Georgia Giant speleothem, Carlsbad Caverns, New Mexico, U.S.A; Sample CB74. Sample collected by Dr. George A. Brook; image generated with the kind help of Dr. John P. Shields of the University of Georgia Center for Advanced Ultrastructural Research. |
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