Report of National Museum, i893^Merrin, 



Plate 6. 



Slab from same block as shown on plate 5, but showing a more advanced stage 



OF oxidation. 



Cat. No. Or.Mi), U. S. N. M. 



The iiercdlatini; solutions i)ermeated along the line extending from the upper left side diagonally 

 downwards toward the right side. 



