diatomite - marine diatomite from the Sisquoc Formation, Upper Miocene to lower Pliocene - teaching hand specimen
Grefco Inc. Palos Colorados Quarry, 7 miles SE of Lompoc, Santa Barbara County, California
Sisquoc Formation, upper Miocene to lower Pliocene
Diatomite is a sedimentary rock formed of microscopic opaline silica skeletons of diatoms, one-celled organisms belonging to the golden brown algae in the class Bacillariophycea. They live both in fresh and in sea water and are one of the most common types of phytoplankton.
As diatoms die, there is a constant rain of their shells to the sea floor or lake bed. These accumulate in thick layers to form a chalk-like siliceous deposit of diatomaceous earth or diatomite. The soft parts of the diatom form a fatty oil that decomposes or becomes petroleum.
The opal in diatomite is metastable, so diatomite changes from opaline diatomite to chert with increasing temperature and pressure. The progression is from hydrous silica (opal a) to anhydrous silica (opal cristobalite-tridymite or opal CT) to either quartz (chert), porcelanite or siliceous mudstone.
This diatomite is marine, deposited in deep water. It was collected in 1988. The quarry is currently inactive.
Diatomite has industrial uses in filtration, in insulation and cat litter, as a filler in rubber, paint, cosmetics and plastics, as a mechanical insecticide and as a stabilizer in dynamite. It is also used as a polishing agent in toothpaste and as a component of some cement blends.
For prepared diatom slides, we recommend Diatom Shop in Italy. Slides are available in scientific and in artistic formats, which are beautiful preparations. You can also purchase unmounted diatoms if you want to prepare your own slides. Diatom Shop has specimens from all over the world.
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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