The distribution of the slate industry among the different States in 1890 is best shown by the following figures, which give the value of the product:
Pennsylvania, $2,011,776; Vermont, $838,013; Maine, $214,000; New York, $130,000; Maryland, $110,008; Virginia, $85,079; Georgia, $15,330; Michigan, $15,000; California, $13,889; New Jersey, $10,985; Arkansas, $240.
Slates are classified in the trade, however, by the name of the region in which they are quarried, some regions extending into two or more States, while several regions are contained in the State of Pennsylvania. The product from each region is more or less distinctive from that of other regions. The more important producing regions are:
Number of Quarries.
Vermont and New York region..................
Bangor region, Pennsylvania.................
Lehigh region, Pennsylvania.....................
Pen Argyl region, Pennsylvania.....................
Northampton hard-vein region, Pennsylvania............
Peach Bottom region, Maryland and Pennsylvania.........
The slates of the Bangor, Pen Argyl and Lehigh regions and the Northampton hard veined slates are found in the extensive slate formation known as the Hudson River Division of the lower Silurian deposits, while the slate formations of Vermont and New York, Maine and the Peach Bottom region, probably belong to the Cambrian Division, whose place in the geological series is lower and older than the Silurian rocks.
"The slates of the Cambrian formation are usually regarded as better in respect to strength and weathering qualities than those of the Silurian age, the market price of some varieties of the former being, indeed, more than double that of the common kinds of the latter."
Vermont and New York Region. - In the western portion of Vermont are extensive quarries of slate, the product being used for all the different purposes for which the material is adapted.
The stone is soft and uniform in texture, and can be readily planed or sawed with a circular steel saw like wood.
The slates from this region vary greatly in color, and are classified and sold under the following names:
Sea-green, unfading green, uniform green, bright green, red, bright red, purple, variegated and mottled.
The true sea-green slate is found only in this State, but it fades and changes color badly.
Red Slate. - Nearly all the red slate used in the United States is quarried in the neighborhood of Granville, near the Vermont line, in New York State. " The slates of this formation are of a brick-red and green color, both varieties often occurring in the same quarry." The slate is of good quality and is almost entirely used for roofing purposes, its color making it especially desirable for fine residences and public buildings. Owing to the limited quantity, this slate brings about three times the price of the dark slates.
Maine Region. - The quarries in this region are located at Monson, Blanchard and Brownville, Piscataquis County. The stone is of a blue-black color, of excellent quality, being hard, yet splitting readily into thin sheets with a fine surface. They are not subject to discoloration, and give forth a clear ringing sound when struck. The Brownville slate is said to be the toughest slate in the world. Slate from this quarry, after fifty years' exposure, looks as bright and clean as when new. The Maine quarries furnish nearly all the black slates used in New England. The product is also extensively used for slates, blackboards and sanitary purposes.