1897.] NATURAL SCIENCES OF PHILADELPHIA. 445 



out here have given great celebrity to the mines of Mednorou- 

 diansk. The celebrated block of Malachite weighing 20,000 pouds 

 (lbs. 720,000, or 360 short tons) was found at a depth of 35 or 40 

 sagenes (245 to 280 ft.) from the surface. In the neighborhood of 

 the limestones the metalliferous rocks become richer in copper salts 

 as the limestones are constantly being dissolved by infiltrating 

 waters. Fossils from these limestones are observed in great number 

 {Pentamerus vogulieus, Atrypa reticularis, Murchisonia Demidoffi, 

 Pleurotomaria ventricosa, Euomphalus subalatus). M. Tscherni- 

 schew concludes that a chemical action takes place at the contact 

 of the limestones and the ore bearing rocks. On the one hand 

 the limestones are dissolved, and from the argillaceous envelope re- 

 sults the insoluble residue. On the other hand the deposits of copper 

 are brought about by the precipitation of this metal, which is carried 

 to the limestone by waters holding it in solution. 



The manganese mines of Tag nil. — About a werst to the northeast 

 of Lebiajaia is found the manganese mine which is exploited by two 

 trenches. The south wall of the south cut exhibiting bright gray and 

 white limestones dipping southwest 60°, and containing Atrypa 

 Jcuchvensis, Spirifer Jcuchvensis, Sp. pseudo-kuchv., Entomis pela- 

 gica, stems of crinoids and corals. Beneath this is a white dolomite, 

 resting on a marble-like limestone, which is in immediate contact 

 with yellow, pink and violet schists, cropping out in the north wall 

 of the mine. North of the schists appear the same limestones seen 

 in the hanging wall, honey-combed with stems of crinoids and corals. 

 Presumably this represents a tightly folded and inclined synclinal 

 of limestone enclosing the schists. The manganese ore is collected 

 in nests and pockets, and seems to indicate a l'elation between its 

 occurrence and the lower Devonic limestone. 



Ascent of Mount Siniaia. — Leaving Taguil and proceeding north 

 through Laia and to Barantcha the road runs on porphyrites and 

 tuffs. From the crossing of the Taguil to the latter place the road 

 crosses gabbros and diallage rocks. The best exposures of the rocks 

 composiug Siniaia are seen in the quarries, which show a diallage 

 alternating with gabbros. Here may be seen excellent instances 

 of Schlieren. The structure is not to be explained by gabbros 

 cutting the diallage rock, for, on breaking it in various directions, 

 even under the microscope, it is impossible to define the limits of the 

 two rocks. 



