QUARRIES IN HANCOCK COUNTY. 
91 
in descending order of abundance, of potash feldspar (orthoclase 
and microcline), slightly smoky quartz, soda-lime feldspar (oligo- 
clase), and black mica (biotite), with accessory magnetite and pyrite. 
The slight contrast between the shade of the quartz and that of the 
feldspar and the small size of the biotite scales produce a general 
lack of brilliancy in the rock. 
The quarry, opened in 1892, measures 300 feet from north to south 
by 300 feet from east to west, and from 5 to 15 feet in depth. It is 
drained by two siphons (2| and 3J inch pipes) 800 and 1,000 feet 
long. The stripping consists of 3 to 4 feet of loam and bowlders. 
Rock structure: The sheets, from 2 to 8 feet thick, are horizontal, 
but on the west side dip 10° W. The courses of joints and dikes are 
o'iven in liir. 9. Joints A recur at irregular intervals. The rift is 
Dike 
W.-E 
S. Wall 
Fig. 9. — Structure at Robertson & Havey quarry, Franklin. 
horizontal and the grain is vertical, striking east-west. Aplite dikes 
measure from 2 to 8 inches in width, and the granite for about a 
foot on each side of them is close jointed. Knots are rather abundant 
and up to 2 feet across. The north-south joint face carries some 
pyrite. Sap measures from 2 to 3 inches in width along the sheets. 
No rust spots were detected. A 1-foot diabase dike, with its rim 
altered to epidote, forms the west wall of quarry, and a 2| to 3 foot 
dike forms the south wall. For a space of 10 feet on each side of 
this dike the shade of the granite has been changed to a dark gray, 
and the rock is rilled with close joints that dip at low angles. The 
microscope fails to reveal the nature of this change, but shows that 
the quartz particles and some of the feldspars are crossed by more 
or less parallel cracks, from 0.25 mm. to 1.25 mm. apart. 
The plant consists of only one derrick and the siphon pipe. 
Transportation is effected by cartage 1^ miles to dock in bay. 
The product is used for curbing, both straight and circular, and 
