It is always a nice day to take a trip to the Guernsey State Park Museum. If you look, hard enough, there is always something new and interesting to discover.
For some reason I became curious about the fire brick, clean and nice, in the Museum Library’s fireplace. Made by the Denver Clay Company they read, Hifire, fire brick.
A quick look at online antique sites, it looks like this type of brick is a good seller, usually selling for around $40 including postage.
The Company came into existence in the late 1870s, and by the 1890s was incorporated and into many types of mining equipment and chemical sales along with the fire brick branch. The building that made the fire brick burned to the ground in 1937 and I could find no record of the fire brick being manufactured there again.
Lots of interesting stories in the park, take a look.