CHARACTER, ORIGIN, OCCURRENCE, AND USES. 
21 
posed blue syenite" shows the chemical alteration of this same rock 
in process of decomposition, while the column headed " kaolin" shows 
the last stage of alteration to kaolin. 
Analyses of pulaskite (blue syenite) and its decomposition products. 
[lirackett & Smith, analysts.] 
Constituents. 
Blue 
syenite. 
Decom- 
posed blue 
syenite. 
Kaolin. 
Silica (Si0 2 ) 
Titanium (Ti0 2 )... 
Alumina (A1 2 3 ) . . . 
Ferric iron (Fe 2 3 ) . 
Ferrous iron (FeO) 
Lime (CaO) 
Magnesia (MgO) ... 
Manganese (MnO) . 
Potash (K 2 0) 
Soda(NaaO) 
Phosphorus (P2O5) . 
Water (H 2 0) 
60.03 
20.76 
4.01 
.75 
2.62 
.80 
Trace. 
5.48 
5.96 
.07 
.59 
50. 65 
.06 
20. 71 
4.87 
.27 
38. 57 
1.36 
.34 
.25 
1.91 
.62 
13.61 
101. 07 
94. 33 
101.00 
Fig. 2.— Residuary clay formed by decomposition of syenite in place, in railway cut 3 miles south of 
Little Rock, sy, Syenite; cl, clay. 
It should be noted that the changes in passing from syenite to 
kaolin consist chiefly in the absorption of water, the removal of the 
more soluble materials, such as lime, potash, and soda, and the con- 
sequent increase of the percentage of alumina. 
This blue syenite is at many places traversed by cracks or joints 
that break it into great angular fragments. Water charged with 
