shale - teaching hand specimens of a hard gray Lower Cambrian shale from the Marble Mountains of California

$ 7.50

This is the Latham Shale, famous as a source of trilobite specimens from quarries in the Marble Mountains of San Bernardino County, California. It varies in color from gray to grayish green. Those quarries are now in the Desert Trails National Monument and are closed to collecting. This material was collected in 2015.

Students should know the basic sedimentary rocks in order of increasing grain size, from mudstone and shale, siltstone, sandstone to conglomerate and coquina.

Shales differ from mudstones in that they are more compressed, form flat plates, and are less likely to disappear in a poof of dust when dropped by a student. This shale is fairly hard and should stand up to student examinations. 

Some shales closely resemble slate, metamorphosed from shale. To distinguish a shale from a slate, the field test is to lick it. The shale will smell muddy. The slate won't. This shale passes the lick-and-sniff test and smells distinctly muddy. 

These specimens ship in a small flat rate box unless combined with other purchases.

Select a specimen: You can select a specimen by telling us what is in the photo with it, a blue or black and silver pen, a black mechanical pencil or one of those plus some number of coins, or you can let us make the selection.

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