420 0. G. Broadhead on Gothic from Missouri. 



very sharply defined, the remainder of the crystals being of aa 

 opaque milky white. 



There being a spring of water in the mine, the water may 

 be sometimes charged with an excess of mineral solutions. 

 The lead has probably been deposited from an aqueous solu- 

 tion and the barite from similar and more recent solutions. 

 The waters also seem to have subsequently held iron oxide in 

 solution as some of the crystals of barite are coated with it. 



A crystal in my possession from the Cord ray mines, but 

 probably from same mine as the above, possesses similar cb&fr 

 3. It is of rhombic form, about two inches long and a 

 half inch thick ; the edges are bevelled by the plains £-i which 

 gave on measurement the angle 77° 40'. It has a border a 

 half inch wide of white opaque barite, the outer angle sharp, 

 inner angle truncated, and the remainder is clear mineral, 

 which corresponds in shape to the cleavage prism ; the direction 

 of the cleavage is also indicated by cracks across the crystal. 

 The white portion of this crystal would seem to indicate 

 alteration, but that can hardly be the cause of the similar 

 appearance of the crystals from the Last Chance mine. 

 2. On the Gothite from Adair County, 3fissourl 



The Coal measures, it is well known, often contain, within 

 the thicker shale beds, interstratified beds of clay ironstone, 

 sometimes in connected layers, at other times in concretionary 

 masses, occurring along a marked horizon. These concretions 

 are often reticulated by calcite veins, one system in concentric 

 lines, the other crossing them ; they are generally termed 



In 1873, while examining the structure of the formations on 

 Chariton River, Adair County, Missouri, I broke open a num- 

 ber of the concretionary masses which were reticulated by 

 veins of calcite from a quarter to half an inch wide, occasionally 

 widening into small cavities one-eighth to one-half an inch 

 high, lined with calcite crystals reposing on the more compact 

 calcite of the vein. Upon and sometimes interpenetrating 

 these crystals are small slender acicular crystals of black 

 gothite, generally not more than an eighth of an inch, but 

 sometimes as much as three-fourths of an inch, in length. The 

 gothite is generally aggregated in bundles at the base of the 

 calcite from which they radiate. Sometimes a single crystal 

 will shoot directly through a calcite crystal. Sometimes also, 

 a single point of a quartz crystal will be seen penetrated in 

 various directions by the gothite. The calcite, often, has its 

 angles bevelled or rounded, and they were sometimes colored 

 red on the surface as was also a little of the gothite. Minute 

 velvety balls of gothite not larger than the one-thirty-second 

 of an inch were also found reposing on the calcite. 



