How THE granite was quarried
Blasting the Stone
FRACTURES AND PLANES
Granite fractures naturally along visible horizontal “sheet” and vertical “joint” planes. At Mohegan, these fractures form large, roughly rectangular natural blocks, which aided quarrying. To make rough quarried blocks rectangular, the blocks were further split along planes called the rift which splits most easily, the lift, and the head which splits with the most difficulty.
Blasting was the first step in the quarrying operation. Workers drilled a row of a few deep vertical holes, filled them with blasting powder, and set off the charges with an electric blasting machine, splitting a large stone from the rock. Then they drilled shallower holes to hand-split large, freshly-blasted stones into smaller stones.
The explosive, known as “black powder,” was made of charcoal, saltpeter and sulfur and was manufactured in large, uniform grains yielding a slower, less powerful explosion that split — but did not shatter — the rock. The explosives were kept in a small stone shed a safe distance from workers at the large quarry and, because they were expensive and dangerous, they were used sparingly.