The Hummelstown
Brownstone Company, was formerly the
Pennsylvania Brown Free Stone Company.
Have you tried:
The
Dauphin County Historical Society, records titled Hummelstown
Brownstone Manuscript Group. I'm sure they will have some good information and advice.
The PA Historical and Museum Commission erected a historical marker in 2005.
Or the PA State Library for the Hummelstown Sun Newspaper or any books they may have.
Including, Ben F. Olena "Hummelstown
Brownstone - Five Quarries Mined the Prized Sandstone from 1867-1929", In:
Pennsylvania magazine, Vol. 19, No. 6, November/December 1996, pages 26-29 with four historical photographs.