NORTH CAROLINA PIEDMONT

N.C.G.S. Open File Report 80-4

CLAYS AND SHALES

OF TIlE

NORTH CAROLINA PIEDMONT

by

Eldon P. Allen N. C. Geological Survey Section

and Kenneth J. Liles U. S. Bureau of Mines

Raleigh 1980

This report is preliminary and has not been edited or reviewed for conformity with North Carolina Geological Survey standards and nomenclature.

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CONTENTS

Abstract . . . .

...

1

Introduction . .

2

Acknowledgements

4

Sample Descriptions, Characteristics, and Evaluations

5

Alamance County

6

Alexander County

11

Anson County

14

Burke County

20

Cabarrus County

25

Caldwell County

30

Caswell County

34

Catawba County

40

Chatham County

44

Cleveland County

55

Davidson County

59

Davie County

63

Durham County .

67

Forsyth County

76

Franklin County

79

Gaston County .

83

Granville County

88

Guilford County

93

Halifax County

97

Harnett County

100

Iredell County

107

Johnston County

113

Lee County

118

Lincoln County

124

McDowell County

128

Mecklenburg County

132

Montgomery County

135

Moore County

144

Nash County . . . .

163

Northampton County

167

Orange County

170

Person County .

174

Polk County . .

180

Randolph County

192

Richmond County

197

Rockingham County

201

Rowan County

206

Rutherford County

210

Stanly County

214

Stokes County

218

Surry County

223

Union County

228

Vance County

232

Wake County .

235

Warren County

245

Wilkes County

250

Wilson County

253

Yadkin County

255

Appendix I - Beneficiation, Chemical, and Mineral Analysis of Five White Residual

Clays .

259

Glossary

....

263

Selected References

266

Illustrations Plate I - Clays and Shales of the North Carolina Piedmont

attached

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ABSTRACT

North Carolina has led the nation in brick production since 1962. and 1979 preliminary figures indicate it has continued its lead with 14 percent of the total U.S. market by producing approxi@ately 1.03 billion bricks valued at $103 million. The state and the U.S. Bureau of tiines established a cooperative program in 1963 to aid in the continuing development of brick capacity and diversity of clay products in North Carolinao

For this program. 380 clay and shale samples were collected from 48 counties in the Piedmont province. The Piedmont includes the state's two major brick producing areas. which are the Triassic basins and the Carolina Slate Belt. Also included are residual clays from miscellaneous rocks and selected sedimentary clays. As a background, 54 clay and shale samples were cOllected from 25 present or recent brick. pipe. or lightweight agregate producers which were active during the 1960's and 1970's.

A total of 326 clay and shale samples were also collected from new localities, of which 188 show potential value in structural clay product applications. These data are included in this open-file report which is placed in the Geological Survey Section Library.

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INTRODUCTION

Traditionally, the bulk of North Carolina's mineral wealth has been in its non-metallic materials, of which clays and shales have been a major part. In 1962, North Carolina became the nation's leading brick producer, and in 1979 it manufactured approximately 1.03 billion bricks valued at $103 million for 14 percent of the total U.S. production.

To aid the producers in a continuing development of North Carolina's brick capacity and help provide for more diversity in the clay products industry, a cooperative program was established by the state and the U.S. Bureau of Mines in 1963. This program provides for the effective coordination of federal and state activities for promoting the exploration and evaluation of local clays and similar non-metallic raw materials for structural clay products and other uses.

On July 25, 1963, two boxes containing 47 clay samples were shipped by motor freight to the Norris Metallurgical Research Laboratory to initiate a long-term, cooperative clay and shale testing program between the U.S. Bureau of Mines and the North Carolina Department of Natural Resources and Community Development, Land Resources Division, Geological Survey Section (formerly the North Carolina Department of Conservation and Development , Division of Mineral Resources). Periodic renewal of this agreement has been made through Fiscal Year 1982.

Under this cooperative agreement, the Geological Survey Section is responsible for: 1) planning and conducting the field work; 2) correlating field, geological, and laboratory data; 3) sampling and delivering samples to a specified laboratory for appropriate pyrochemical testing to determine the potential economic applications; and 4) publishing the findings of the program. The U.S. Bureau of Mines conducts or provides for testing and related evaluations. Reports of the program findings are reviewed and approved by the U.S. Bureau of Mines prior to pUblication.

Some clay and shale samples have been collected from all regions of North Carolina; however, this report coverS only the Piedmont province. The Piedmont includes the state's two major brick producing areas, which are the Triassic basins and the Carolina Slate Belt. Also included are residual clays from miscellaneous rocks and selected sedimentary deposits. Samples for this report have been collected from 48 Piedmont counties.

Test data have been compiled on 380 clay and shale samples--90 clays and shales from the Triassic basins, 107 residual clays and shales from the Carolina Slate Belt, 145 residual clays from miscellaneous rocks, and 38 sedimentary clays. Of the 380 total samples, 326 are from new localities, of which 188 show a potential value in structural clay product applications.

To provide a background for comparison with materials presently or recently utilized, 54 samples were collected from the 25 producers who were active during the 1960's and 1970's. The terms present use or recent

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