GRIMSLEY. | Gypsum Mines and Mills. 63 
working than the Hope gypsum, since it holds good thickness 
and quality wherever found, while the Hope layer varies in 
different parts of the area. When the earth deposits are ex- 
hausted these rock deposits will again command attention and 
the rock will be quarried for plaster manufacture. 
Secondary Gypsum Deposits in the Central Area. 
At a number of places in the central Kansas area occur im- 
portant secondary deposits of gypsum which form the basis of 
the greater portion of the plaster manufacture. The material 
is locally called ‘‘stucco,”’ ‘‘ gypsum dirt,” and other similar 
names. Itisa granularearth, found in low, swampy ground, dark 
colored in place; but on drying it assumes a light ash-gray 
color. It is soft, incoherent, so that it is readily shoveled into 
cars, and is ready for calcining with less labor and expense 
than is required in working the solid rock. 
At the present tine four,of these deposits are opened in the 
central area, plaster being now made at three of them, a fifth is 
worked to the north in Clay county, and a sixth is opened to 
the south in the northern part of Butler county. 
DISCOVERY AND EXTENT OF THE ARBAS. 
The first deposit was discovered in the spring of 1873 near 
Gypsum City, by Mr. John Tinkler, in running a fire-guard 
around a field. Two years later he calcined some of the earth 
in an ordinary thirty-eight gallon kettle and used the plaster in 
the cellar of his house, where it still remains good. In 1889 he 
with others formed the Saline County Plaster Company and 
built a mill at the edge of town. This was afterwards sold to 
the Acme Cement Plaster Company, but they no longer use the 
mill or deposit. In 1892, 7000 tons of plaster were sent from 
this mill to Chicago for the World’s Fair buildings and a medal 
was awarded the company in recognition of the qualities of their 
plaster. It has been used in the government buildings at Forts 
Riley and Leavenworth, and the product has been shipped to 
all parts of the United States. 
