AEKANSAS. 
53 
Stratton and Kelley's property in S. 29, T. 3 S., R. 28 W., shows a red slate strik- 
ing N. 70° and dipping 43° N. In the northeast quarter of the same section the 
National Slate Company has an opening. 
Black and gray slates in large smooth slabs are exposed on the Brennan and McEl- 
wen property in the northeast quarter of S. 30, T. 3 S., R. 28 W. The cleavage in 
these outcrops strikes N. 70° W. and dips 13° N. 
The Barden quarry in 8. 25, T. 3 S., R. 28 W., shows good black slate, striking 
N. 65° E. and dipping 20° N. 
Chemical composition of Arkansas slates. — The following analyses of Arkansas root- 
ing slates are fairly representative of the composition of these materials: 
Analyses of slates, Montgomery County, Ark. 
[Analyst, W. G. Waring.] 
Silica (Si0 2 ) 
Alumina ( A1 2 3 ) 
Ferric oxide (Fe 2 3 ) . . 
Ferrous oxide (FeO) . . 
Lime(CaO) 
Magnesia (MgO) 
Potash (K 2 0) 
Soda (Na 2 0) 
Sulphur in S0 3 
Sulphur in FeS 2 
Carbon (C) 
Carbon dioxide (C0 2 ) 
Water 
66.16 
8.62 
9.04 
3.44 
1.77 
.78 
4.96 
.64 
.08 
.02 
2.10 
.09 
.18 
68.79 
14.26 
5.90 
1.16 
1.40 
1.43 
3. 09 
.09 
.44 
.01 
2.01 
.11 
.47 
69.04 
12.66 
8. 55 
1.30 
1.75 
1.87 
2.98 
.09 
. 06 
.01 
Tr. 
64.00 
11.59 
L3. 71 
1.56 
2.03 
1.36 
. til 
.05 
.04 
4.03 
.01 
.57 
63. 22 
16.76 
9. 5 1 
L.75 
1.52 
I. 13 
.70 
.05 
.03 
3. 70 
.01 
1 . 0] 
1. Green slate, quarry No. 2. 
2. Red slate, quarry No. 2. 
3. Red slate from State House Cove. 
4. Hard red slate from State House Cove. 
5. Green slate from State House Cove. 
6. Black slate from west end of Crooked Creek vein. 
7. Black slate from Crooked Creek Falls. 
MICROSCOPIC ANALYSES OF ARKANSAS SLATE. 
By T. Nelson Dale. 
The microscopic analyses of Arkansas slates published in 1904, Bull. U. S. Geol. 
Survey No. 225, p. 414, have been revised and are here repeated and supplemented 
by several new ones of specimens collected by Mr. Eckel during his recent visit to 
the quarries of that State. 
Black slate from Mena, near Big Forks. This is a pure black slate, which to the 
unaided eye has an exceedingly fine texture and a remarkably smooth cleavage sur- 
face with a slight luster. It is both carbonaceous (or graphitic) and magnetitic; does 
not effervesce with cold dilute hydrochloric acid, is very sonorous, and very fissile. 
Under the microscope this slate shows a matrix of muscovite (sericite), with a very 
brilliant aggregate polarization and an unusually fine texture and great homogeneity. 
Quartz grains are few and not over 0.01 mm. in diameter. Rutile needles unusually 
minute. Many opaque particles of irregular shape, some of which are pyrite, others 
magnetite, and some coaly or graphitic matter. No carbonate. 
The constituents, arranged in descending order of abundance, appear to be mus- 
covite (sericite), carbonaceous or graphitic matter, quartz, pyrite, magnetite, and 
rutile. 
