INDEX. 
153 
Page. 
Roofing slates, analyses of 34-36 
composition of 39-42 
production of 131 
Rosen busch, «EL, on slates 12-13 
on shear zones 29 
Roth, Justus, on slates 13 
Rupert, Vt., shear zone at, plate showing.. 30 
slate deposits at 31 
Rutile in slates, occurrence of 11-13 
S. 
San Francisco Slate Co., slate quarry of 58 
Scales in slates, occurrence of 11 
Schists, definition of 5 
relations of slates and 10-1 1 
Sea-green roofing slate, occurrence and 
character of 104-106 
Sedgwick, Adam, on joints 28 
on slip cleavage 24 
Sericite in slate, occurrence of 11 
Shale, transition of, to mica slate 10, 81 
Shales, Paleozoic, analyses of 37 
Sharpc, Daniel, on cleavage 25, 27 
Sharpe and Phillips, on slaty cleavage 23 
Shear zones, occurrence of 29, 31 
plate showing 30 
relations of joints, dikes, and 44 
Shenandoah Slate Co., slate quarry of 121 
Slate Hill, Pa., slate quarry at 28 
Slate needles, occurrence of 13-14 
Slate-pencil slate, description of 109 
Slates, characteristics of 124-125 
chemistry of 34-42 
elasssifi cation of 6, 125 
cleavability of 45 
See also Cleavage. 
compression of 34-37, 39 
corrosion of 48 
definition of 5-6, 10 
deposits of, location of, map showing.. 5 
formation of 7 
origin, theory of 5-9 
unsettled questions concerning. . 10-11, 13 
prices of 125 
strength of, tests showing 47 
thin section of, plate showing 64 
toughness of 47 
uses of 5 
See also Clay slates; Mica slates; Ash 
slates; Dike slates; Igneous slates; 
Roofing slates; Slate-pencil slates; 
Mill-stock slates. 
Slatingion, Ark., slate deposits of 52 
Slatington, Cal., slate deposits at 56 
Slatington, Pa., quarries near, structure in. 82-83 
ribbon at, removal of, view of 84 
slate deposits at 75, 81, 124-125 
map of 80 
structure in, figures showing 82-83 
slate of, analyses of 8'4 
Slaty cleavage, definition of 9 
plate showing 26 
production of 8 
Slip cleavage, description of 24-25 
plate showing 26 
synonyms of 25 
Page. 
Snowden.Va., slate deposits at 115-117,124 
slate quarries at, location of, map show- 
ing 116 
Sonorousness, lack of 70 
tests for 45 
Sorby, H.C.,on petrography of slates 10-11,13 
on slaty cleavage 22-23 
Southern States Portland Cement Co., slate 
and cement of 60 
Southwestern SlateManufacturingCo., slate 
quarries of 52, 55 
slate deposits of &5, 124 
Specific gravity, determination of 47 
Spotted slates, analyses of 15-17 
occurrence of 15-18 
specific gravity of 47 
Staurolite in slate 11 
Steiger, George, analyses by 73-121 
Stokes, H.N. .analyses by 37 
Strain-slip cleavage. See Slip cleavage. 
Stratton & Kelley, slate deposits of 53 
Structure, account of 5, 18-34 
views of 18, 20, 22, 26, 30 
Sphene in slate, occurrence of 11 
T. 
Talc in slate, occurrence of 11, 69 
Tennessee, slate deposits of, description of. . 88 
slate of, analysis of 88 
production of 126-131 
Terms used, glossary of 146-147 
Testing, manner of 45-49 
Texture, character of 6-8 
Thetford, Vt,, slate deposits at 89 
Thiirach, H., on slate characteristics 13 
Thurston, Md., slate quarries near 69-70, 124 
Tilden, W. C, analysis by 121 
Toughness, determination of 47 
Tourmaline in slates, occurrence of 11 
Turner, H. W., on shear zones 29 
Tyndall, John, experiment by 8 
U. 
Ulrich, E. O., on age of Arvonia slate forma- 
tion 113 
Unfading and seagreen slates, boundary of. 101 
Unfading green roofing slate, description 
of 106-107 
Utah, slate of, analysis of 89 
production of 126-131 
V. 
Van Hise, C. R., on cleavage bands 32 
on slate 9 
Variegated slate, description of 107, 108 
Veins, quartz, occurrence of 32-33, 43 
plate showing 22 
Vermont, Northfield Township, slate quar- 
riesof 90-93 
slate deposits of, location of 89-90 
slate deposits of, location of, map show- 
ing 88 
sections across, descriptions of 94-99 
pla te showing 90 
structure of 101-103 
