'-) -\ ^ 



DESCRIPTIVE NOTES OF QUARRY DISTRICTS AND QUARRIES -^^^ 



appear changed to kaolin, and the hypersthene is badly 

 decomposed.* 



Grindstone Island, Jefferson County.- — ^A red oranite is 

 quarried extensively on this island in the St. Lawrence 

 river, north-west of Clayton. There are many outcrops, 

 especially on the western side of the island, and small 

 quarries have been opened at more than twenty different 

 points. 



There are three large quarries which are worked exten- 

 sively and with little Interruption. The granite of these 

 quarries Is rather coarse-crystalline, red to bright red in 

 color and consists of flesh-colored feldspar, quartz and mica, 

 with very little magnetite as an accessory constituent. Its 

 resemblance to the Scotch granite has given It the name 

 of '' International Scotch granite." Examined under the 

 microscope the feldspars show kaolinlzation. The dura- 

 bility of the stone is witnessed In the unaltered or scarcely 

 altered rock which crops out on the two sides of the quarry. 

 Blocks of large size can be obtained up to the limit in hand- 

 ling and shipping. An examination of a representative 

 specimen of this granite shows that It has a specific gravity 

 of 2.713, equivalent to a weight of 169 pounds per cubic 

 foot. The absorption test indicated 1.55 per cent of water 

 absorbed. The loss in a dilute solution of sulphuric acid 

 was 0.13 per cent. Freezing and thawing produced no ap- 

 parent change. Exposure to a temperature of 1200 to 

 1400 degrees F. caused vitrifaction, destruction of color 

 and Impaired the strength so that the specimen crumbled 



* Tests of the strength of this stone made by Dr. Thos. Egleston, of Columbia College 

 School of Mines, show that it stands 27,000 pounds and breaks at 29,000 pounds to 

 the square inch. Dr. Egleston's series of tests made for the company show further, 

 that when heated to a bright red heat by a blast of a Bunsen burner the stone was 

 not cracked badly; and, at a temperature of 800° -1350° F. and then quenched in 

 cold water the specimens changed in color but otherwise were hardly altered, except 

 at the highest heat. "The outside of the piece was rendered rather crumbly and 

 granular * * * but the piece as a whole was still hard and resists moderate 

 blows of the hammer." [From report made to the Ausable Granite Works.] 



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