SHALE, S-80.  California. Dark
gray, moderately to very fissile marine shale.

Difficult to cut thick pieces. Tends to part along

layers once a hammer makes hearty contact.

This is the classic  Mariposa, California 

subduction zone margin shale that has been uplifted

into the Sierra foothills.

LIMEY SHALE, S-80A. California.
Somewhat fissile, pink to purplish gray-brown.
Effervesces and partly dissolves in acid.  Check.

SHALE, S-80B.  Colorado. Kerogen
or petroleum bearing "Green River Shale".
Also referred to as dolomitic marlstone.

SILTSTONE, S-85. California.
Light purplish gray. Lacustrine.

SILTSTONE, S-85A. California.
Light brownish, grayish or 

grayish brown to pinkish-red and a rose-purple color.

A wide range of colors and again lacustrine.

LIMEY SILTSTONE, S-85B. 
California. Pinkish gray. Some effervescence
in acid.

SINTER (CALCAREOUS), see under TUFA under
LIMESTONE

TRAVERTINE, S-90. California and various.
Calcium carbonate deposited often at the mouth of a hot spring
or in a limestone cave. Various colors from white
to tan, brown, yellows and reds in alternating bands and layers.
The larger the piece the better the layering and banding are displayed.

TUFA, see under LIMESTONE