Removing the stone
DRILLING AND SPLITTING
Three different techniques were used to drill and split the large blocks of stone. Over the quarry’s five decades of operation, hand drilling was replaced with steam drilling, which in turn was replaced in the mid 1920’s with compressed air drilling fed by aboveground pipes. The introduction of new drilling and splitting methods led to a one third increase in the amount of marketable stone the quarry was able to produce.
WEDGE AND FEATHER SPLITTING
Invented about 1800, this splitting method involved hand, and later machine-drilling a row of small, closely-spaced holes a few inches deep, placing iron wedge and feather tools in the holes, and tapping across the row of wedges until pressure split the stone, ideally on a flat plane. This method was used for quarrying and splitting into smaller blocks. Shallow “dog holes” chipped in opposite sides of the blocks provided grip for lifting hooks.
DEEP HOLE SPLITTING
This uncommon method used wedge and feather splitting with alternating short and long holes. Steam-powered mechanical drills for long hole drilling were invented in the 1870s and were replaced after 1900 with compressed air models. At Mohegan, granite was difficult to split on flat, perpendicular planes, wasting the limited supply of golden granite. Deep hole splitting controlled the splitting, resulting in flatter planes, less waste and more usable stone.
A tripod air drill used for deep hole splitting | Source: Milestone Heritage Consulting
This efficient mechanized method for extracting large blocks involved drilling rows of closely-spaced holes with a compressed air drill mounted on a horizontal bar, and then using a wide “broaching” bit to drill out the webs between the holes. A few strategically-placed blasting powder charges freed the block from the quarry wall. Broach channeling was faster and lower in cost than other splitting methods. It also helped the Mohegan Quarry conserve the most desirable stone.
Quarrying generated large quantities of “grout,” a Scottish word for rock rejected for poor splitting or quality. Workers lifted grout from the pit with derricks and discarded it in grout piles. The largest piles, extending downhill from the pit, were built using short railways running along their tops.
THE BLACKSMITH SHOP
A blacksmith shop housed a forge, anvil and tools for repairing equipment. Among the blacksmith’s most important tasks was sharpening tools including worn rock drill bits. This skilled job was done entirely by hand until Grenci & Ellis installed a compressed air-powered drill sharpener in the mid-1920s.