The quarry in Westford yields Chelmsford Grey, a light gray stone of fine to medium grain, highlighted by small black flakes. The quarry has been in continuous operation since 1881, even staying open during both World Wars when other quarries were shut down. During these times, it also furnished ballast for ships in addition to its regular product line.
Stone is extracted with twist wires and a loose abrasive system. During the extraction process, massive sections of stone are “opened†or prepared for sawing with oxygen burners, which create channels that run down two sides of a particular section that is to be sawn. The stone between the burned channels is then quarried in a traditional manner to facilitate setting the saw towers. Then, large towers -- each fitted with 8 to 10 wires -- create horizontal cuts. To finally free the stone, a pin is inserted into the slabs of stone, and they are lifted out of the quarry as needed. Overall, it takes eight or nine weeks to prepare a defined section and extract the stone from a specific location within the quarry.