coal. 3 87 



the coal in tin; Denver fieM, and in its fuel ratio, L.33, falls into the higher 

 class. 



No. 128, from the Simpson mines is a typical specimen of "bono coal." 

 Its fuel ratio is 0.95, approaching the lignites in this respect. Its ash 

 amounts to 33.52 per cent. Its water content is 1 L.43 per cent. 



No. 129, from the Acme mine, is a specimen of lilirons, woody, lustrous 

 coal. It is low in ash, of medium range among the prairie coals in its water 

 content, and has a fuel ratio of 1.31, showing it to be somewhat below the 

 variety of which 127 is a sample. 



SECTION II.— THE CLAYS OF Tin: DENVER BASIN. 



The economic clays of the Denver Basin are derived from the Pleis- 

 tocene, Denver, Laramie, Fox Hills, and Dakota formations, the Denver 

 and Laramie, however, affording but a small proportion of the total yield. 

 The clays of the Dakota are refractory and are employed in the manu- 

 facture of fire-brick, crucibles, and allied products; those of the other 

 formations are of the ordinary type, and are manufactured into brick and 

 tile for general architectural purposes. 



FIRE-CLAY. 



The fire-clay of the Dakota occurs in noncontinuous bands, 5 to 15 



feet thick and several hundred in length, in the argillaceous shales which 

 separate the two or three heavy layers of sandstone that constitute the 

 bulk of the formation. Numerous openings have been made upon them 

 in the vicinity of Clear, Bear, and Deer creeks, and at other, less access- 

 ible points along the foothills, within and beyond the confines of the 

 Denver Basin. With the exception of those near Golden the openings are 

 prospects. 



The mines near Golden are in the hogback about 2 miles north of 

 the town. Several bodies of fire-clay here occur immediately beneath the 

 upper heavy sandstone, access being by tunnel through this. 



On the next two pages analyses of several of the typical clays of this 

 country and Europe are tabulated, together with the uses in which the 

 clays are employed 



