50 GEOLOGY AND MINERAL RESOURCES OF MISSISSIPPI. 
CLAYS AND CLAY INDUSTRIES. 
The most important mineral industry of Mississippi is that based on her clay resources. 
The clay industries are, as yet, not so well developed as the abundant supplies of good 
clays would justify. This lack of development is due, in part, to lack of published informa- 
tion regarding the variety and extent of the clay deposits of the State, though difficulties 
in regard to transportation and markets have also retarded the growth of these industries. 
Recent and prospective improvements in railroads and the steady growth of the villages 
and cities of this section will doubtless aid greatly in advancing the brick and pottery indus- 
tries of Mississippi. 
According to the statistics collected by the United States Geological Survey, the clay 
industries of Mississippi during the years 1900 to 1904, inclusive, produced brick and pot- 
tery valued as follows: 
Production of pottery and brick in Mississippi, 1900-1904- 
Year. 
Pottery. 
Brick. 
1900. 
1901. 
1902. 
1903. 
1904. 
$14, 452 
4,779 
14, 424 
14,295 
14, 701 
$558,916 
451,694 
501,785 
658, 491 
710,878 
During 1903, according to the statistics gathered in the recent geologic survey of the 
State 9 potteries and 86 brick plants were in operation; most of these plants were visited 
and samples of their clays and product were placed on exhibition at the St. Louis Exposi- 
tion. In 1904 there wen 1 92 plants reported as engaged in the clay-working industry. 
The clays of the State can be described most conveniently under nine headings, accord- 
ing to the geologic groups in which they occur. These are as follows: (1) Clays of the 
Tuscaloosa formation (lower Cretaceous); (2) Porters Creek clays (lower Eocene); (3) 
clays of the Wilcox formation (Eocene); (4) clays of the Jackson formation (upper Eocene); 
(5) clays of the Grand Gulf group (Miocene?); (6) Lafayette days (Quaternary); (7) loess 
and yellow-loam clays (Quaternary); (8) Quaternary clays of the Gulf coast; (9) Quater- 
nary clays of the Yazoo delta. 
In the description of the clays by formations the general rule will be followed, as far as 
possible, of naming them by localities from north to south. 
CLAYS OF THE TUSCALOOSA FORMATION (LOWER CRETACEOUS). 
The lower portion of the Tuscaloosa formation is largely made up of plastic clays rang- 
ing in purity from white kaolin to a common sandy brick clay. They have been used to a 
small extent in the manufacture of ordinary stoneware and fire brick, and some of the purer 
clays have been used successfully in making china ware. 
They occur in horizontally bedded strata, often immediately overlain by the Lafayette 
sands. In the northern area of the Tuscaloosa the clays of this group outcrop very fre- 
quently along the streams where the thick mantle of Lafayette has been removed. Many 
of the clays immediately underlying the Lafayette are more or less discolored by iron oxide 
from the overlying formation. 
Iuka clay. — At Iuka, Tishomingo County, and for 6 miles north occurs a pink to mottled- 
purple clay, highly plastic and free from sand. It is found at Lake Como, one-fourth mile 
east of Iuka, and in numerous branches to the east and north. In some places the clay 
resembles the bauxite of Arkansas. It has small round spots through it the size of a pea. 
These spots are much deeper red than the rest of the clay. The analysis given below shows 
it to be high in alumina and ferric oxide, which gives the clay its pink to red color. A large 
amount of this clay has been mined and shipped from Iuka for making paint. 
