468 MINERALS. 



of arenaceous quartz rock skirts it on the west. This band of gneiss is better developed 

 in Massachusetts than in Vermont, although in the former state its peculiarities have not 

 been much investigated partly because much of it passes beneath the Connecticut 

 River sandstone of mesozoic age. 



This band of gneiss leaves Vermont in the north part of Vernon, but reappears in 

 Westminster and Rockingham at Bellows Falls. The granitoid gneiss is well developed 

 at Bellows Falls. Upon the New Hampshire side it forms a high mountain called Kil- 

 burne Peak. Its most southern point in Vermont is in the north part of Westminster. 

 The rocks in the gorge at the falls in Connecticut River, from whence the name of the 

 village, afford a better exhibition of the characters of this rock than at any other place in 

 the State. The rock is filled with several systems of joints, so that it is difficult to ascer- 

 tain the true position of the planes of stratification. Veins of granite are common in the 

 ledges, and the cavities in the gneiss contain beautiful crystals of wavellite and fluor spar. 

 West of Bellows Falls this rock forms a hill, and southwest of the village it has been cut 

 through by Saxton's River. It does not extend a great distance north of Bellows Falls in 

 Vermont. Perhaps an area of two square miles is underlaid by the gneiss in this patch 

 in Vermont. It does not show itself again in the State, in a recognizable form, unless 

 it be the same with the granitic range from Waterford to Maidstone. There are many 

 points of similarity between the two bands of rock. 



The thickness of the gneiss in Vermont must be very great. The section across Mount 

 Holly may perhaps give an average of its thickness. About 8,000 feet of strata have been 

 removed there, of which we should estimate about 6,000 to have been of gneiss. Yet as 

 the bottom of the formation may not be reached here, the true thickness may be greater. 



MINERALS IN GNEISS.* 



(Those italicised are found either iu talcose schist or calciferous mica schist, and have already been 

 described.) 



J&yanite, Wavellite, Fluor, Alum, Staurotide, White Augite, Prehnite, Chiastolite, Adularia, Tourma- 

 lin, Indicolite (variety of Tourmalin), Calcite, Fibrolite, Dolomite, Micaceous Iron Ore, Magnetic Iron, 

 Native Gold, Scolecite, Zoisite, Tremolite, Stilbite, Finite, Pyrites, Andalusite, Calcite, Actinolite, Red 

 Hematite, Octahedral Iron, Asbestus, Orthoclase, Chlorite, Massive Garnet, Steatite, Rhomb Spar, Serpen- 

 tine, Epidote, Staurotide Quartz, Galena, lolite, Graphite Anthophyllite, Chrysolite in Dike. 



Wavellite. A subphosphate of alumina with a trace of Fluohydric acid. Primary form a right rhom- 

 bic prism. Usually occurs in hemispherical implanted globules, with radiated structure. Color white, 

 yellow, green and gray. Found in Vermont at Bellows Falls. 



Fluor Spar. Primary form, a cube. Chemical composition, fluorine and calcium. Color white, wine- 

 yellow, violet-blue, emerald-green, pistachio-green, sky-blue, rose-red, and common red (rare.) This min- 

 eral furnishes some of the most highly colored specimens in the cabinet, and is used in the massive 

 state for making vases and similar ornaments, known as Derbyshire spar. It is found in Vermont at 

 Bellows Falls and Putney, and is in the Collection No. 49 (Presented by A. D. Roe.) 



Alum. This occurs as an incrustation, or more properly an efflorescence, upon many rocks. It is a sul- 

 phate of alumina, soda, potash, ammonia, magnesia, etc. The primary form is set down as a cube. It has 

 been found in Vermont at Bethel, Colchester, Somerset, Halifax, and Newfane. 



White Augite. This is merely a handsome variety of Pyroxene, known sometimes by the name of diop- 

 Ride and white malacolite. It is found in Vermont at Whitingham, and can be seen in the Cabinet under 

 the Nos. 168 and 169. 



*By E. Hitclicodc, jr. 



