An aside comment: The sawdust referred to was from basswood and was actually made at the Philadelphia Mint !
Here's an excerpt from a September 1885 inventory of equipment:
"One circular saw built by the Rollingstone Manufacturing Co."
"One circular saw and screen for making sawdust for Coiner’s uses."
(The full machinery/equipment list will be in More Mint to Mint.)
Here's a letter confirming the use of basswood for sawdust:
May 21, 1892
Superintendent,
Mint U.S.
Philadelphia, Penna
Sir:
Referring to your letter of April 2nd, in explanation of the entry in your statement of earnings and expenditures for the quarter ended December 31, 1891, of eleven dollars and ninety cents ($11.90), for sawdust furnished the Carson Mint, you are informed that this amount should not appear in this statement. As the amount was to reimburse you for the basswood and labor in converting the same into sawdust, you are informed that it should have been deposited in the Treasury as proceeds of material sold. In order to reimburse your appropriation, the proper way would have been for your to have rendered a bill to the Department when an account would have been stated, and the amount transferred on the book of the Department from the appropriation for the Carson Mint to those of your Mint.
It will therefore be necessary for you to deposit this amount in the Treasury as proceeds of material sold.
Respectfully yours.
Robert E. Preston,
Acting Director of the Mint