QUARRIES IN KNOX COUNTY. 
131 
ide), and that warm dilute acetic acid extracts 0.07 per cent of 
CaO (lime), and a trace of MgO (magnesia). This, if the C0 2 is 
allotted to the CaO, shows a percentage of 0.08 of CaCO ;? (lime- 
carbonate), the presence of which mineral is also indicated by the 
microscope. The stone takes a fine polish, but the size of the mica 
plates does not favor the durability of the polished face under con- 
tinued exposure. The contrasts of color and shade are chiefly 
between the two feldspars and the black mica. 
The quarry, opened before 1860, now measures about 500 feet from 
northeast and north-northeast to southwest and. south-southwest and 
about the same distance from northwest to southeast, and ranges in 
depth from 20 to 75 feet, averaging about 40 feet. The excavation 
has not only cut down a granite hillock, but has extended below the 
general land level. PI. VI, .1. shows the south-southeast end of the 
Pig 
50. — Structure ;'.t Sands quarry, Vinalhaven. 
quarry. The surface drainage, as well as the water that exudes from 
between the sheets, is collected in the deeper, now unused parts of 
the quarry and supplies the boilers. No stripping seems to have 
been necessary. 
Rock structure: The sheets, from 1 to 20 feet thick — generally, 
however, from 2 to 10 feet — lie flat along an east-west axis for a 
width of about 200 feet, but on either side curve over gently to the 
north and south, with dips of 5°, 10°, and 20°. The joint and vein 
purses are shown in fig. 20. Joints B form the northwest and south- 
east walls of quarry. Joints C are coated in places with crystal- 
line calcite to the thickness of one-fourth inch, or with hematite, 
chlorite, and stilbite in microscopic films. (Determination of stil- 
bite by Mr. W. T. Schaller, of the United States Geological Survey.) 
The rift is vertical, with a N. 80° W. course. The " hard-way " or 
