Table 4. Key for Identification of Common Shales and Fireclays

Step 1.0 Examine the fractured butt end of the core to determine the character of the fractured surface and examine the sides for the presence of dark bands or streaks.

1.1 If the fracture is-

planar or shaley and the sides are without dark streaks or bands (e.g. 70L), proceed to step 2.

1.2 If it is-

planar or shaley and the sides have dark streaks or bands at or nearly at right angles to the sides of the core (e.g. 74L), proceed to step 3.

1.3 If it is-

irregular (some slickensides and/or irregularly oriented dark streaks may be present) (e.g. 75R), proceed to step 4.

1.4 If it is-

somewhat irregular or mixed planar and irregular (may show some wavy dark streaks nearly at right angles to the side of the core), (e.g. 74R), proceed to step 5.

Step 2.0 Determine the color of the core.

2.1 If the color is-

black (e.g. 70R), the rock is a Black Shale or 114.*

2.2 If it is-

dark gray (e.g. 71R), the rock is a Dark Gray Shale or 124.*

2.3 If it is-

light gray or light greenish gray or tan (e.g. 72R), the rock is a Light Gray Green Shale or 134.

Step 3.0 Determine the character of the dark streaks and the color of the core.

3.1 If the dark streaks are-

coal and the overall color of the core is black (e.g. 73L), the rock is a Black Shale with Coal Streaks or 113.

3.2 If they are-

coal and the overall color of the core is dark gray (e.g. 73R), the rock is a Dark Gray Shale with Coal Streaks or 123.

3.3 If they are-

shale and the color of the core is black, the rock is a Black Layered Shale or 112.

3.4 If they are-

shale and the overall color of the core is dark gray (e.g. 74L), the rock is a Dark Gray Layered Shale, or 122.*

Step 4.0 Determine the color of the core.

4.1 If the color is-

black (e.g. 75L), the rock is a Black Fireclay or 117.

4.2 If it is-

dark gray (e.g. 75R), the rock is a Dark Gray Fireclay or 127.

4.3 If it is-

light gray or light greenish gray (e.g. 77R), the rock is a Light Gray Green Fireclay or 137.

Step 5.0 Determine the color of the core.

5.1 If the color is-

dark gray (e.g. 74R), the rock is a Dark Gray Churned Shale or 125.

*These rocks in some cases contain fossil shells. Please see page 79.