362 BELL ON THE VALUE OF 



be the cause of the green spots in the purple slate, they form a 

 very objectionable feature, being liable to decompose under the 

 weather, and allow the rain to leak through the roof. A small speck 

 of iron pyrites can generally be detected in the centre of each of 

 the spots, and these may have had something to do with their 

 formation. The slate quarries of western Vermont have a common 

 disadvantage, in the low underlie of the cleavage, which in several' 

 cases is less than 20 degrees, thus requiring a much larger expen- 

 diture in working, than when the cleavage is vertical, or under- 

 lying at a high angle to the horizon. In some of the quarries 

 the underlie, which is always to the eastward, is from 20 to 40/ 

 degrees, but unless the angle is sufficiently high to give a self- 

 supporting hanging wa'l, a great loss is incurred in removing or 

 supporting the superincumbent mass. 



About a dozen quarries are worked on the western belt. The 

 principal one is the Eagle Slate Quarry, situated a mile south of 

 Hydeville, and which produces about 10,000 squares a year. Here 

 the underlie of the cleavage, which nearly coincides with the dip- 

 of the strata, is at an angle of only 17 degrees. Roofing slates 

 alone are made at this quarry, and bring from $2.50 to $3.50 a. 

 square at Hydeville depot. In the township of Castleton, the 

 West Castleton Railroad and Slate Company manufacture 150 

 squares of slate a month, besides sawing from 15 to 16,000 square 

 feet of slab slate. The cleavage here underlies to the eastward 

 at an angle of 40 degrees. In 1857, the second year of operation, 

 the sales of the produce of this quarry amounted to $60,000. 



A planed surface of slate is found to retain remarkably well the 

 compounds used in enamelling, even in the presence of heat or 

 acids, and hence slab slate can be marbleized and used in a great 

 variety of ways. The western Vermont slate is marbleized for 

 jambs and mantelpieces, table and bureau tops, billiard beds and 

 kerosene lamp bottoms. These are successfully made to imitate 

 all kinds of ornamental marble, and are sold in immense numbers 

 at one fourth the price of real marble. The cost of marbleized 

 mantels varies from 10 to 125 dollars, according to the workman- 

 ship which has been expended upon them. Writing slates are 

 also prepared in great numbers at the western quarries ; and there 

 is a large demand for unplaned slabs for sanitary and other pur- 

 poses. The foregoing facts in regard to the slates of Vermont are 

 condensed from Prof. Hitchock's report on the geology of the- 

 state. 



