Ironstones are very common rocks in the Southern Appalachian Coal Fields and are frequently found in the form of small plates and nodules in most shales and some sandy shales (e.g. 71L). Ironstone in beds thick enough to be logged (i.e. four to six inches) is relatively rare, occurring mainly in the following forms:

Nodular Ironstone 076 80L
Massive Ironstone 074 80R
Oolitic Ironstone 077 81L

These specimens have been exposed to the air for some time and have a characteristic orange color. When freshly cored, most ironstones are pale orange or buff and some are dark gray.

Limestones are much less common than ironstones. They can be easily distinguished from other fine-grained rocks because they are hard, dense and brittle and effervesce readily when a drop of 10% hydrochloric acid is applied to them. The colors of limestones vary from black to light gray and some have a faint orange tint. Many limestones contain fossil shells of marine animals and these should be carefully logged as they are in some cases important as "marker" beds in identifying coal seams. The most common limestone types are:

Massive Fine Grained Shaley Limestone 804 81R
Massive Fine Grained Shaley Limestone with Fossil Shells 894 82R
Massive Fine Grained Limestone with Fossil Shells 994 82L and upper 83R

Flint Clay is a very rare rock type but its association with some coal beds (e.g. the Hazard No. 4 seam in Kentucky) makes it important as a marker bed. Flint clay is not illustrated in this book but it can be very easily differentiated from other fine-grained rocks by its extreme brittleness and hardness. (Pure varieties will scratch the head of a steel hammer.) In addition even the smallest fragments are non-slaking and remain sharp and hard even after long exposure. This rock type can be logged as follows:

Flint Clay 090 (example from Pittsburgh region)