480 MINERALS. 







Range and Extent. 



The principal range of this rock is the calciferous schist. This, as the map shows, ex- 

 tends through the whole State, and occupies, probably, a third of the surface. In the 

 southern part of the State it is narrow, and much of it seems to be replaced by gneiss. 

 Nor can the geologist have much doubt that in some way or other, whether we can or 

 cannot understand the chemistry of the metamorphosis, it has been changed into gneiss. 

 In the neighborhood of Ascutney it is natural to refer such a change to the protrusion of 

 the great mass of granite forming the mountain. But the same effect does not seem to 

 have been produced further north by still larger masses of granite, and what geologist 

 will suppose the influence of a melted Ascutney could have extended nearly a hundred 

 miles south ? The more probable supposition is, that the more general and extended 

 agency that changed the schist into gneiss, produced also the granite. That rock every- 

 where is found to have played a less important part in uplifts and metamorphisms than 

 was formerly supposed. It seems often to be itself a product of metamorphism. 



Of the narrow range of mica schist in the northeast part of the State we can say but 

 little. The foregoing list shows its strikes and dips as observed by us. 



Minerals in the Calciferous Mica Schist* 



These are Black Tourmaline, Scapolite, Spodumene, Rutile, Ilmenite, Garnet, Pyrites, Pyroxene, Feld- 

 spar (Orthoclase), Quartz, Washingtonite, Chalcopyrite or Copper Pyrites in immense beds, Kyanite, Calcite, 

 Zoisite, Epidote, Wad, Actinolite, Mispickel, Copperas (alluvial), Galena, Magnetic Iron, Native Copper, 

 Bog Ore (alluvial), Pyrolusite, Malachite, Tufa, Agaric mineral, Staurotide, Albite, Graphite, Marl, 

 Adamsite, Molybdenite. 



Tourmaline. The primary form is a rhombohedron often in secondary forms, with trihedral summits. Its 

 colors are black, brown, blue, green, red, and colorless. The chemical composition shows it to contain 

 silicate of alumina, boracic acid, protoxyd of manganese, and in some varieties lithia, soda, lime and 

 potash. The principal ores found in Vermont are the black crystals occurring in pure white quartz, and 

 owing to the contrast between the jet black tourmaline and the milk-white quartz, they form very hand- 

 some cabinet specimens. They cannot, however, be used in the place of jet, because they are so extremely 

 brittle that they will not bear cutting. One of the most remarkable localities of tourmaline in the world is at 

 Paris, Me., and its first development is owing to the labors of Prof. C. U. Shepard. The crystals occur of 

 different colors, ranging from pale-pink to garnet-red, as well as green. Some of these have been cut and 

 polished, and form the most beautiful gems hitherto found in the United States. Some varieties of tour- 

 maline which are of a smoke color, are used in the construction of instruments for polarizing light. The 

 principal localities of black tourmaline in Vermont are Newfane, Vershire, Cavendish and Barnet. The 

 specimens of black tourmaline in the State Cabinet are Nos. 277 to 296 inclusive. 



Scapolite. This crystallizes in right square prisms, and consists of silicate of alumina, lime, soda and 

 protoxyd of iron. Its localities are in Marlboro, Guilford and Brattleboro. 



Spodumene. This mineral is not found in distinct crystals in Vermont, but in Norwich, Mass. In this, 

 the only locality in the world where it occurs in crystals, it is found to be an oblique rhombic prism. Its 

 essential chemical composition is silicate of alumina and lithia, and hence is it a source from which lithia is 

 often obtained. Its color is grayish-white or greenish, and at Norwich, Mass, it often occurs of a pinkish 

 color, probably owing to the manganese in the triphyline, which is found in close connection with it. It 

 has been found as yet only in Brattleboro. 



Rutile. This mineral is titanic acid, or the oxyd of titanium. It occurs in shining red crystals, as 

 the term "Rutilus" implies, from which Rutile is derived. In form it is a right square prism. Twin 



*By E. Hitchcock, jr. 



