Newcomb Tourmalines. 7 



.zircon, niuscovite, smoky quartz, scapolite, albite, graphite, tremolite, 

 pyroxene and pyrite. 



The difference between the enclosed minerals is even greater than 

 between the limestones within and without this area. The tourma- 

 lines are occasionally of very large size ; one crystal measures eight 

 inches in length by four inches in breadth, or twelve inches in cir- 

 cumference. Excepting on the surface, and thus exposed to weather- 

 ing, the crystals are all remarkably fresh in appearance. They are of 

 a rich brown or green color (rarely greenish-black and subtranslu- 

 cent, from depth of color), and perfectly transparent. A large 

 number were found entirely free from flaws and furnished beautiful 

 gems, though of small size. The greater number of the stones thus 

 cut were fragments of crystals. A number of crystals were found, 

 however, of the length of five to ten mm., doubly terminated and 

 without a flaw. Larger crystals, from one to two cm. in diameter, 

 are very clear and are translucent notwithstanding their many flaws. 

 Fragments, which would cut a fine stone, may often be broken from 

 these crystals. 



These tourmalines show no new or even rare faces. The zero 

 plane is of infrequent occurrence. The general habit of the crystals 

 is short and stout. They often exhibit a parallel growth of a large 

 number of crystals, having a common termination with adventitious 

 crystals of shorter length along their sides. The phenomenon be- 

 fore mentioned, of one crystal having a single termination at one end 

 and several at the other, is here of frequent occurrence. These crys- 

 tals also enclose large rounded globules of calcite, and occasionally of 

 quartz. Graphite and scapolite are of more rare occurrence. It 

 not infrequently happens that large, beautiful and apparently perfect 

 crystals turn out to be no more than thin shells or series of shells, 

 enclosing masses of calcite. Sometimes one termination will be per- 

 fect, with the body of the prism a mass of cells ; or the prism faces 

 will be apparently perfect, while the terminations are entirely want- 

 ing. Thin plates with the polished surfaces of the R-faces are very 

 common. Finally, fragments of quartz and scapolite are often found 

 with innumerable fine veins filled with tourmaline. 



Another mineral of common occurrence in this locality is sphene 

 or titanite. It is found in very small, tabular-shaped crystals, and 

 more rarely in crystals of eight cm. or more in length, and with corres- 

 ponding dimensions. In color the crystals range from nearly black 

 to chocolate, brown, red and clear honey-yellow ; varying from 

 opaque to semi-transparent. 



